Thursday, May 8, 2014

Cain: Marked for Life (Genesis 4:15)

Why did God put a mark on Cain? So no one would kill him (Genesis 4:15)

After humanity has been exiled from Eden (Genesis 3:24), the first brothers born on earth, Cain and Abel, decide to offer sacrifices to God (Genesis 4:3). Presumably they are attempting to rebuild humanity’s relationship with the estranged deity (Genesis 4:3). Cain, a farmer, offers “the fruit of the ground” while Abel, a shepherd, brings “the firstlings of his flock” (Genesis 4:3-4 NASB). Though the text offers no explanation as to why, God favors Abel’s offering (Genesis 4:4-5). In response, a dejected Cain coaxes his brother into a field where he kills him (Genesis 4:8-9). The act marks the first premeditated murder.

When confronted by God, Cain is informed that the ground will no longer sustain him and that he will survive as a fugitive (Genesis 4:10-12). In effect, Cain is homeless and unemployed.

Cain seemingly laments his punishment more than his crime; he pleas with God claiming that the consequences are too great (Genesis 4:13-14). Ironically, the murderer also confesses that he fears being murdered. Cain’s plea bargain is successful. God assures him that if murdered he will be avenged sevenfold and then ratifies this agreement by marking Cain (Genesis 4:15).

So the Lord said to him, “Therefore whoever kills Cain, vengeance will be taken on him sevenfold.” And the Lord appointed a sign for Cain, so that no one finding him would slay him. (Genesis 4:15 NASB)
John Byron (b. 1967) summarizes:
The final aspect of the “sentencing phase” the mark of Cain in Genesis 4:15b. As part of God’s apparent promise of divine protection against a premature death, Cain is given a mark from God. The stated purpose of the mark was to prevent anyone from killing Cain. (Byron, Cain and Abel in Text and Tradition: Jewish and Christian Interpretations of the First Sibling Rivalry, 119)
Jurist Alan M. Dershowitz (b. 1938) evaluates:
Cain murdered his younger brother and then tried to cover it up [Genesis 4:8-9]. His motive was petty jealousy over God’s unexplained preference for Abel’s offering. Yet despite the severity of the crime, God is relatively soft on Cain. God does not impose proportional punishment. Instead He makes him a fugitive and a wanderer [Genesis 4:12]. Being excluded from the clan could, of course, carry serious consequences in primitive society, since it returned the excluded person to the state of nature and exposed him to the elements as well as animals. (This may explain Rashi [1040-1105]’s interpretation of “the mark of Cain” as restoring the fear of Cain in animals.) Even in early England, being denied the protection of the “king’s peace” was dangerous. But at least there was a chance of survival by the resourceful outsider. It was not capital punishment. (Dershowitz, The Genesis of Justice: Ten Stories of Biblical Injustice that Led to the Ten Commandments and Modern Law, ii)
In modern terms, Cain’s plea bargain waives the death penalty and imposes life in prison. In doing so, God insures that the cycle of violence will not escalate. There will be a moratorium on murder. Still, Cain serves forever as a cautionary tale.

Cain’s petition marks a pivotal point in the narrative (Genesis 4:14). Walter Brueggemann (b. 1933) pinpoints:

The crucial element is the exchange between the offender and the judge (Genesis 4:13-15). The sentence is that he be a fugitive, consigned to keep farming land that has no life in it (Genesis 4:11-12; cf. Genesis 3:17-19, 4:2). But the pause in the action is when Cain seeks mercy. The killer now fears to be killed (Genesis 4:13-14). The killer has no resources of his own but must cast himself upon the mercy of the life-giver. And such a mercy: a mark asserting both guilt and grace [Genesis 4:15]. (Brueggemann, Genesis (Interpretation: A Bible Commentary for Teaching and Preaching), 60)
Far from a tyrant, the deity allows the human to get a say in his future. Thomas L. Brodie (b. 1940) contemplates:
At first, the divine word is supreme, creating all things (Genesis 1:1-2:4a). Then, in settling humankind in the Garden (Genesis 2:4b-24), the divine command, while still respected, is open to being contravened, broken. Later, in the eating, it is indeed broken (Genesis 3:1-7). Finally, Cain not only goes against it, but manages even to reverse it: his plea to Yhwh to change the decree of punishment (Genesis 4:6-8, 12-15). Thus, there is a strong contrast between the transcendent freedom of the opening command, “Let there be light [Genesis 1:3],” and the pressurized closing command not to kill Cain; the God who once pronounced with total sovereignty becomes Yhwh who takes up the logic of a distressed murderer (“Therefore/Very well,” Genesis 4:15). At the end, God’s word is interwoven with the word of a banished wanderer. (Brodie, Genesis as Dialogue: A Literary, Historical, and Theological Commentary, 155)
Cain fears that “anyone who meets me may kill me” (Genesis 4:14 NASB). This statement is controversial as to this point Genesis has only mentioned three other people living on earth: Adam, Eve and God. Though Cain’s fears could be real they might also be imagined: The convicted killer could be projecting his own murderous intentions onto others.

C. John Collins (b. 1954) considers:

We should read Genesis 4 under the assumption that the author is using Cain’s speech as a way of showing the readers the condition of Cain’s inner life. He could be afraid—perhaps God even considered the fear to be legitimate, since he put a “mark” on him (Genesis 4:15)—of what his siblings might carry out in due course, along the lines of what came to be known as the “avenger of blood” (see Numbers 35:9-34, where it is presented as an institution already familiar to the audience who received the Pentateuch)...It is also possible that the author wants us to think that Cain’s fears are exaggerated, the result of his evil deed upon his conscience. In this case God put a mark on Cain in order to reassure him. (Collins, Did Adam and Eve Really Exist?: Who They Were and Why You Should Care, 112-13)
God promises Cain that he will be avenged sevenfold should his fears become realized (Genesis 4:15). In effect, God will do for Cain what God did not do for Abel.

In addition to his words, God provides a tangible sign (Genesis 4:15). Martin Sicker (b. 1931) infers:

Cain failed to appear satisfied with the Creator’s blanket assurances. Unable to deal with such intellectual abstractions and hypothetical situations, he required something more readily accessible to his senses, upon which he relied so heavily. Cain needed a sign, perhaps an omen, something he could fix his gaze upon, something he could sense. Accordingly, the biblical author suggests that the Creator, exhibiting extraordinary patience and tolerance, gave Cain the omen he felt he needed so desperately. (Sicker, Reading Genesis Politically: An Introduction to Mosaic Political Philosophy, 59)
Cain is bestowed a “mark” (CEV, ESV, HCSB, KJV, MSG, NIV, NKJV, NLT, NRSV, RSV) or “sign” (ASV, NASB) (Genesis 4:15). The Hebrew ’ôth, can also mean “token”. Given this ambiguity, the mark has generated much speculation.

Russell Jacoby (b. 1945) questions:

The translation of the Cain-Abel story into the Jewish-Christian conflict stumbled on a critical problem...God “set a mark upon Cain, lest any finding him should kill him.” The Lord wanted him marked but not killed (Genesis 4:15). God seemed to be playing a Talmudic joke, since the text offers no clue as to the nature of this mark. Philo [20 BCE-50 CE], an Alexandrian Jew, in his commentary puzzles about the obscurity. The Lord, Moses tells us, put a mark upon Cain, “but what his mark is, he has not shown, although he is in the habit of explaining the nature of everything by sign.” How is Cain to be identified? What is the mark? How do we know who is the Cain among us? After all, Cain is your brother and looks like everyone else, which is the problem. (Jacoby, Bloodlust: On the Roots of Violence from Cain and Abel to the Present, 83)
Kenneth A. Mathews (b. 1950) analyzes:
The “mark of Cain,” as it is popularly known, has proven to be a seedbed for confusion (Genesis 4:15b). “Mark” is the common word for “sign” (’ōt); the exact nature of the sign or its place on the body (“on Cain”) is unknown. One Jewish tradition pointed to Cain himself as the “sign” who served to admonish others to repentance (Genesis Rabbah 22.12). In effect this has become true for later generations, if not his own, for Cain the man has become a token of sin’s fruit and divine retribution (I John 3:12; Jude 1:11). Although “sign” is used figuratively in several passages (e.g., Exodus 13:9; Deuteronomy 6:8, 11:18), the only parallel is Ezekiel 9:4, where certain men receive a mark on the forehead. But even there it is an extended vision in which it only has symbolic force. What is important here is its purpose: “so that no one who found him would kill him” (Genesis 4:15). “Mark” in our passage is not a sign of the “curse”; in fact, it assures Cain’s safety rather than acts as a reproach. The mark in Ezekiel’s vision had the same effect; it distinguished those who bore the brand and gave them protections. (Mathews, Genesis 1-11:26 (New American Commentary), 278)
The “Mark of Cain” has developed ominous connotations. Nahum M. Sarna (1923-2005) clarifies:
This phrase has been persistently misunderstood. The reference is not to a stigma of infamy but to a sign indicating that the bearer is under divine protection. Hebrew ’ot here probably involves some external physical mark, perhaps on the forehead, as in Ezekiel 9:4-6, serving the same function as the blood of the paschal lamb smeared on the lintels and doorposts of each Israelite house in Egypt [Exodus 12:7, 13, 22, 23]. It is also possible, though less likely, that the “sign” consists of some occurrence that serves to authenticate the divine promise as being inviolable. In that case, the text would be rendered: “The LORD gave Cain a [confirmatory] sign that no one who met him would kill him.” (Sarna, Genesis (JPS Torah Commentary), 35)
Hugh C. White (1936-2001) laments:
Those who seek to kill will be killed; they will become victims of their own hostility...But there must be a mechanism by which this process will be set in motion, and this is a divine sign which is given or placed on Cain. The Hebrew is ambiguous (אות)...Whatever its outer form, its significance in this context is to establish a communicative relation between the character and the divine Voice. Cain will not be granted such micro-dialogues in the future. But a trace will remain of this word to him in the form of a material mark or sign apparently on his body...And there is the chief irony. The narrative began with Cain seeking spiritual identification with the divine through the sacrifice of material representations of his person...Now he is to be deprived of all hope of attaining such identification with the land and with the divine..Through it he will be reminded of this dialogue in the past with the divine judge which fixed his sentence as a curse, and the mercy by which he was granted this protecting mark...The physicality of this sign, which is now the organizing center of his identity, permanently bars him from any future attempts to attain identity with the divine. His identity is forever based upon a sign which imposes upon him its own temporal and material form. The mark thus functions as a type of inverted promise, a material sign which marks Cain in an autonomous mode of existence, closing his development as a character by guaranteeing his life against attack at the price of eternal liminality, and alienation. (White, Narration and Discourse in the Book of Genesis, 166)
Whatever the mark is, it should be perceived as an individual, not communal, distinction. That is, it likely applies only to Cain. Claus Westermann (1909-2000) determines:
There is no direct parallel which can clearly prove the individual or collective explanation. There are distinguishing marks like this both for individuals and for groups. One comes to a decision by looking at the content and meaning of the narrative as a whole — and the context points clearly to an individual mark. (Westermann, Genesis 1-11 (Continental Commentary), 313)
The mark has long perplexed those wanting to visualize it and countless theories as to the mark’s substance have been posited. Given the fruitless conjecturing, some commentators simply ignore the issue.

John Byron (b. 1967) acknowledges:

It is not known what the mark was and all that can be said is that it was probably something visible. The Septuagint adds nothing to our understanding when it translates the mark as a “sign,” and there is nothing strikingly different among the other extant translations. And exegetes, for the most part, did not comment extensively on the Mark of Cain. For instance, in his Questions and Answers in Genesis, Philo [20 BCE-50 CE] does address God’s giving of the mark, but the focus of the question and subsequent commentary is on why the mark was given, and no speculation over the nature of the mark is provided. Josephus [37-100], too, avoids the topic by failing to even acknowledge that part of the story. The avoidance of the topic by interpreters may be symptomatic of their preoccupation with the seven-fold punishment of Genesis 4:15a and Genesis 4:24. Or it could be that they simply chose to ignore the mark since very little information is provided and it does not really support the overwhelming urge to rewrite Genesis 4:15 so that Cain’s punishment is magnified. (Byron, Cain and Abel in Text and Tradition: Jewish and Christian Interpretations of the First Sibling Rivalry, 119-20)
Despite the reticence of many to comment on the nature of the mark, countless theories have been posited. Claus Westermann (1909-2000) introduces:
In what form did the mark appear? Imagination has been unbridled here. Johann Adolph Bühlau has collected the older opinions, De signo Cain posito, 1713, Karl Fruhstorfer [1875-1956] the more recent. The most common is that it was a tattoo mark or an incision on the face, a different way of arranging the hair, circumcision, etc. One may mention as one among many, a Rabbinic suggestion, Bereshit rabba 22:12: God gave him a dog as his companion. (Westermann, Genesis 1-11 (Continental Commentary), 314)
John H. Sailhamer (b. 1946) adds:
What is the “sign”? The narrative does not explicitly say, though many attempts have been made to identify it, e.g., as a bright-colored coat or a horn on his forehead (Ludwig Diestel [1825-1879], Geschichte des Alten Testaments in der christliche Kirche [Jena: Mauke’s (Hermann Dufft), 1869], 497). (Tremper Longman III [b. 1952] and David E. Garland [b. 1947], Genesis ~ Leviticus (Expositor’s Bible Commentary), 102)
Irven M. Resnick (b. 1952) reviews:
Most Jewish commentators viewed Cain as a repentant sinner, which explains why his punishment—to become a wanderer—was comparatively so light. But there were many variant traditions concerning the sign that marked Cain. Pirke de Rabbi Eliezer and, later, Rashi [1040-1105] understood the sign of Cain placed on Cain’s forehead to be one of the letters of the divine name. Other commentators—both Jewish and Christian—speculated that the sign was a horn on Cain’s forehead. Rupert of Deutz (d. 1129) insisted that in Scripture the sign placed on Cain was not a tremor in his body, or a horn on his forehead, or some other such thing. These are merely fables among the Jews. But Andrew of Saint Victor (d. 1175) noted that Cain was a vagabond, a wanderer, fearful, and that he sustained a “trembling in the members” (tremor membrorum) as a sign. Even more explicitly Hugh of St. Victor (d. 1141) avers that the sign of Cain is a “trembling of the members like one who is mad or insane.” Petrus Comestor (d. c. 1178) identifies the sign, similarly, as a tremor or shaking of the head, and Peter the Chanter (d. 1197) combines this tremor about the head with a mind seized by fear. (Resnick, Marks of Distinctions: Christian Perceptions of Jews in the High Middle Ages, 209)
James M. Dean (b. 1943) further documents:
Early and medieval exegetes tended to imagine Cain’s mark as a physical stigma of some kind. Early Jewish commentary, perhaps influenced by descriptions of other divine signs such as the mark of Tau (Ezekiel 9:4, 6), postulated a letter from the tetragrammaton (Targum Psuedo-Jonathan) or the alphabet (Pirque Rabbi Eliezer 21) placed either on Cain’s forehead or his arm (Louis Ginzberg [1873-1953], Legends of the Jews 1.111-12). Some Christian writers, following the Septuagint of Genesis 4:14, which reads “trembling and grieving” where the Vulgate has “vagus et profugus” (“a fugitive and a vagabond”, King James Version), understand the mark as an involuntary shaking of the head (Peter Comestor [d. 1178], Historia Scholastica: Liber Genesis [Patrologia Latina 198:27]; Peter Riga [1140-1209], Aurora, 418). As þe lyff of Adam and Eve puts it: “And þo sette Crist a mark upon him, þat he waggede alway forþ wiþ his heved” (Sammlung altenglischer Legenden [1878], 224). In Cursor Mundi the Lord places writing on Cain so that others may “read” it “als clerk” (1178), and in the Cornish Creation, God makes the sign of omega (ω) on Cain’s forehead (1179), a mark which could resemble horns...From Cain’s curse, according to medieval tradition, arose the monstrous races—the Grendels, Calibans, anthropophagi, and Apeneck Sweeneys — thought to exist in inhospitable regions (John Block Friedman [b. 1934] [1981], 89). (David L. Jeffrey [b. 1941], A Dictionary of Biblical Tradition in English Literature, 481)
Abraham Kuruvilla updates:
Genesis Rabbah 22:12 suggests, rather incredibly, that God gave Cain a dog that would accompany him in his wanderings, scaring off potential assailants! R.W.L. Moberly [b. 1952], working off the preposition “for” (ל, l, “sign for Cain”), rather than the expected “on” (על, ’l, as in Exodus 13:16; Deuteronomy 6:8, 11:18, where signs are placed “on” bodies), thinks that the proverb-like saying “Whoever kills Cain is in danger of being avenged sevenfold” (Genesis 4:15) is, itself, the sign—a sign “for” Cain’s protection, rather than a sign “on” Cain’s person. In any case...the sign on Cain indicated his sin/guilt; but it also served as a token of God’s mercy upon the sinner—Cain was not to be killed in vengeance by anyone. Cain is banned, but he is still blessed: “[h]e leaves Gods presence, but not God’s protection.” H.G.L. Peels [b. 1956] notes the irony that “Yahweh wants to be the keeper of the man who did not want to be his brother’s keeper.” (Kuruvilla, Genesis: A Theological Commentary for Preachers, 84)
There are no exact parallels to the mark of Cain though there are comparisons to be made. Claus Westermann (1909-2000) researches:
What could well be a direct parallel is found in Nuzi Tablets. Jacob J. Rabinowitz [b. 1928] sees a connection between the banishment and a sign, Vetus Testamentum 11(1961) 55-59; Nuzi IV 369, 42 speaks of a condemnation: “It means banishment, excommunication.” An outline of the fate of the condemned is then given: “The procedure described in ana ittišū sounds very much like excommunication and the shaving (of the head) there like a sign of excommunication. There is perhaps an allusion to the sign of excommunication in Cain’s sign (Genesis 4:15),” p. 59. Pieter Middlekoop [1895-1973] thinks that one of the functions of the mark is to protect the person responsible from the consequences of the murder: he links it with Exodus 4:24-26 (South East Asia Journal of Theology, 8 [1966-67] 17-28). (Westermann, Genesis 1-11 (Continental Commentary), 313)
Most interpreters have assumed that the mark is on Cain’s body. John E. Hartley (b. 1940) surmises:
The mark must have been visible so that anyone coming upon Cain would at once be aware of the protection Cain was under. This mark condemned and simultaneously protected Cain; whoever killed Cain would suffer vengeance seven times over. [Genesis 4:15] That is, the slayer would be judged to the fullest measure. (Hartley, Genesis (New International Biblical Commentary), 84)
M.W. Collier rationalizes:
Placing a mark upon him implies the other inhabitants of their small world would be able to recognize it as having been placed by God. If not, then the marking of Cain would have served no purpose. Since the book implies that the mark had purpose, then we must assume the other people called to the same God. If they did not then thy would have not have any fear of retribution from Cain’s God. (Collier, The Good Book? Chapter 1 Book 1 Genesis 1-50, 29)
Hermann Gunkel (1862-1932) asserts:
The mark that Yahweh gives Cain was, naturally, on Cain’s body. It belongs “to the realm of religious tattooing and stigmatization, which, widely dispersed, was also known to Semitic peoples” (Wilhelm Heitmüller [1869-1926], Im Namen Jesu, 174; Ezekiel 9:4; Isaiah 44:5; Leviticus 19:28; Deuteronomy 14:1f; Revelation 13:16f, 14:9; Galatians 6:17, etc.). According to the circumstances of the narrative, the mark of Cain was not, as the popular view maintains, a mark meant to designate Cain as a murderer (such as the haggard expression of the murderer) but a mark intended to protect him from murder (August Dillmann [1823-1894]). Whereof it consisted, the narrative...does not say. (Gunkel [translated by Mark E. Biddle (b. 1957)], Genesis (Mercer Library of Biblical Studies), 46-47)
Some have presumed that God places a letter on Cain like Hester Prynne, the protagonist in Nathaniel Hawthorne (1804-1864)’s Scarlet Letter (1850).

Robert Gnuse (b. 1947) studies:

Many commentators suggest that the mark upon Cain was a tattoo, for that was the most logical mark on a person’s body in the ancient world. It is also suggested that the mark was on his face, perhaps his forehead, since that was the most common place in the ancient world to put a distinguishing mark. It was visible to a stranger, especially if the Kenite were garbed in such a way as to protect his body against the wind and sand of the wilderness. Elsewhere (Ezekiel 9:4) there are references to a protective mark placed upon the forehead. In later years such a protective mark was the letter tau, the last letter of the Hebrew alphabet. Some authors suggest that the mark on Cain’s forehead was the tau (Wilhelm Vischer [1895-1988] 74-75; Alan Richardson [1905-1975] 85). In the two or three centuries before Jesus, the Hebrew letter tau was placed upon important religious manuscripts or in the margins of manuscripts next to especially significant verses, such as those which might contain the sacred name for God. The letter appears to protect something or highlight it as sacred. This would be true of both people and written manuscripts. The form of the tau that was used was written in an old Paleo-Hebrew script, not the tau used in the script of the Hebrew Bible (and learned dutifully by Jews and Christian seminarians when they study Hebrew). (Gnuse, Misunderstood Stories: Theological Commentary on Genesis 1-11, 166-67)

There is an oft cited biblical parallel to a protective mark upon the head in the prophet Ezekiel (Ezekiel 9:4-6). Victor P. Hamilton (b. 1952) compares:

Another Hebrew word for “sign,” taw, also functions as a symbol of identity. In his vision Ezekiel sees God’s executioners coming on the city. They are told to “put a mark” on those who truly grieve over the city’s sins (Ezekiel 9:4). When destruction comes those who bear the “mark” are to be spared (Ezekiel 9:6). The Hebrew word for “mark” is taw, which is the last letter of the Hebrew alphabet. In the older Hebrew script it was shaped like an X. Some early Christian exegetes saw here an anticipation of the saving power of the cross, an interpretation which is apologetic and forced, though this Ezekiel passage does serve as a background for all the references to “marking” in the book of Revelation [Revelation 7:3, 9:4, 13:16-17, 14:1, 9, 17:5, 20:4, 22:4]. (Hamilton, The Book of Genesis, Chapters 1-17 (New International Commentary on the Old Testament Series), 235)
Many have compared the mark of Cain to a tattoo. In fact, Cain has even be viewed as an icon of such markings. Karin Beeler (b. 1963) documents:
In his book I Love Mom: An Irreverent History of the Tattoo, John Gray [b. 1946] identifies Cain as the bearer of the first tattoo: “And the Lord set a sign for Cain, lest any finding him should smite him” (Genesis 4:15)...According to Gray, God’s marking of Cain brands Cain as “the first rebel” (Gray 25). What is important about the marking of Cain is that the Biblical narrative links the concept of the tattoo to violence and to the marginalized status of the criminal. Cain’s tattoo functions as a sign of difference and resistance to the Law. The narrative of Cain’s murder and his ensuing outcast status are embedded in the visual power of the “sign,” which Gray has chosen to call a tattoo. Yet Cain’s tattoo also has an ambiguous, perhaps even a subversive, function, because when God the divine tattoo artist marked him, He not only marginalized him but also marked him as God’s “property” to protect him from harm. Thus Cain is still branded as belonging to someone; while this does not have the same resonance for a gang member or prisoner who might benefit from relations with another gang member or prisoner, the mark of identification serves as a way of signaling a kind of ownership. (Beeler, Tattoos, Desire and Violence: Marks of Resistance in Literature, Film and Television, 118)
Another prominent theory historically is that Cain is afflicted with habitual trembling. This premise is influenced by the Septuagint. Russell Jacoby (b. 1945) traces:
The Septuagint, or Greek version of the Hebrew Bible, translated the curse of Cain as trembling and groaning. Early Christian writings adopted this interpretation, and shaking also became a mark of Cain. In a Christian text from the sixth century called The Conflict of Adam and Eve, Cain trembles from fear as he buries Abel in the earth. An angry God condemns Cain to perpetual trembling. “Then Cain trembled and became terrified; and through this sign did God make him an example before all the creation, as the murderer of his brother.” This idea has persisted virtually to the present, for instance in a twentieth-century Catholic Bible, which reprises an earlier commentary: “The more common opinion of the interpreters of holy writ supposes this mark [of Cain] to have been a trembling of the body.” The mark of Cain, then, consisted of two components, trembling and wandering. (Jacoby, Bloodlust: On the Roots of Violence from Cain and Abel to the Present, 84)
Ruth Mellinkoff (1924-2011) deduces:
That the mark of Cain was a trembling of Cain’s limbs (in general and not necessarily only his head) must have some early popular support, for we learn of it through its condemnation by Rupert of Deutz (ca. 1075-1129), the theologian who attempts to trounce all who accept such an interpretation. In his comments on the Genesis text Rupert emphatically denies that the trembling of the limbs was the mark of Cain. Rupert’s denial is of further interest because in it Rupert demonstrates a sophisticated interpretation of the grammar in Genesis 4:15 whereby Cain is the sign...Posuitque Cain [in] signum, meaning “made Cain [as] a sign.” Rupert, aware of the grammatical possibilities of the biblical passage, says that Cain became the sign of the Lord, thereby representing the Lord’s proclamation; and therefore Cain as the sign was the symbol of the ruler which must not be violated. (Melinkoff, The Mark of Cain: An Art Quantum, 51)
It cannot even be stated with certainty that the mark is actually on Cain’s person. Martin Kessler (b. 1927) and Karel Deurloo (b. 1936) recognize:
What is the sign? It cannot be the so-called “sign of Cain” marking a murderer, for Cain was painfully blessed. The narrator leaves our questions unanswered and does not even indicate whether it is a sign on or for Cain. One might fill in with what it signifies, namely, life. (Kessler and Deurloo, A Commentary on Genesis: The Book of Beginnings, 66)
J.G. Vos (1903-1983) notes:
The words “the Lord set a mark upon Cain” may be more accurately translated, “the Lord gave Cain a sign [Genesis 4:15].” The Hebrew says, literally, “the Lord gave a sign to Cain”; it does not say that the sign was “in” or “on” Cain. (Vos, Genesis, 93)
Barry L. Bandstra (b. 1951) dissects:
לקין. Beneficiary > prepositional phrase: preposition + noun proper ms. Typically translated on Qayin, for example NRSV: And the Lord put a mark on Cain [Genesis 4:15]. This makes it sound like a tattoo. Yet the structure looks more like a Beneficiary than a Circumstance of location, which might be expected to use prep ב or על. (Bandstra, Genesis 1-11: A Handbook on the Hebrew Text, 261)
The belief that the Mark of Cain is not on his body has generated advocates. John Byron (b. 1967) surveys:
Those who do not think a visible mark is in the mind of the author include Gordon J. Wenham [b. 1943] who follows P.A.H. de Boer [1910-1989] (Nederlands Theologisch Tijdschrift 31 [1942]:210) in suggesting that the sign is Cain’s name which sounds like “shall be punished.” “His very name hints at the promise of divine retribution of his attackers” (Wenham, 109). R.W.L. Moberly [b. 1952] (“The Mark of Cain—Revealed at Last?,” Harvard Theological Review 100 [207]:11-28) offers that God’s promise to Cain, “Whoever kills Cain will suffer vengeance,” is the “non-corporeal sign and thus, the sign and the promise are not two different things, however closely related” (15). (Byron, Cain and Abel in Text and Tradition: Jewish and Christian Interpretations of the First Sibling Rivalry, 119-20)
Countless other non-corporeal theories have been posited. R.R. Reno (b. 1959) notes:
The text gives no clue as to the nature of the mysterious mark. An Aramaic version of Genesis, however, suggests that God lends Cain the power of his holiness as a protection against retribution: “Then the Lord traced on Cain’s face a letter of the great and glorious Name, so that anyone who would find him, upon seeing it on him, would not kill him” (Michael Maher [1933-2012] 1992:34)...This reading may seem fanciful, but the larger canonical context encourages an interpretation of the mark along these lines. (Reno, Genesis (Brazos Theological Commentary on the Bible), 108-09)
James M. Dean (b. 1943) chronicles:
Some have interpreted the mark as a psychological punishment (Philo [20 BCE-50 CE]) or an unspecified “sign of perdition” (Hugh of St. Victor [1096-1141], De Vanitate Mundi, 3). Both St. Ambrose [337-397] (De Cain, 2.9.34-37) and St. Augustine [354-430] (Contra Faustum 12.13) allegorically equate Cain with the Jewish people and with the race which killed Christ. In Beowulf (1264) Cain is said to have been “marked by [or for his] murder” (morphe gemearacod). From such interpretations derived from the notion that the mark of Cain was his twisted personality, his despair, as Geoffrey Chaucer [1343-1400]’s Parson says, “of the mercy of Jhesu Crist” — in which he was linked to Judas (Parson’s Tale, 10.1015). Lord Byron [1788-1824]’s Cain cries out that his brow “burns” with the mark, “but naught to that which is within it” (Cain, 3.1.500-501). (David L. Jeffrey [b. 1941], A Dictionary of Biblical Tradition in English Literature, 481)
David W. Cotter records:
Ambrose [340-397] says that he is marked by his slavery to sin, that henceforth he belongs to sin as surely as any slave belongs to an owner: “Like a slave, Cain received a mark and he could not escape death. Thus is the sinner a slave to fear, a slave to desire, a slave to greed, a slave to lust, a slave to sin, a slave to anger. Though such a man appears to himself free, he is more a slave than if he were under tyrants.” (Cotter, Genesis (Berit Olam: Studies in Hebrew Narrative & Poetry), 45)
John H. Sailhamer (b. 1946) supposes that the mark of Cain is actually the city he builds (Genesis 4:17) and that it serves as a prototype for later cities of refuge (Numbers 35:9-15):
The major issues in this brief narrative are similar to those in the account of the “cities of refuge” (Numbers 35:9-34). In both narratives God provides protection against one who “avenges the blood” of another. The initial question addressed in these narratives is not whether one is guilty of the crimes of murder—that was to be settled by due process (Numbers 35:12). The issue that links the narratives about Cain and about the cities of refuge (in Numbers 35:9-34) is the need for protection of the accused against the threat of revenge. God’s intention in both texts is to put an end to further bloodshed: “Bloodshed pollutes the land” (Numbers 35:33)...The background of the cities of refuge may provide a much-needed clue to the meaning of the “sign” or “mark” (Genesis 4:15b) given Cain. The purpose of the “mark” (or “sign”) was to protect Cain from vengeance: “so that no one who found him would kill him.” Though it is sometimes assumed that a “mark” was “put on” Cain (cf. the early versions), the passage states only that a sign was given “to” or “for” Cain (wayyāśem...l‘qayin ‘ôt, literally, “and he [the LORD] appointed to Cain a sign”; cf. Genesis 21:13, 18, 27:37, 45:7, 9, 46:3 with Genesis 21:14, 44:21)...An important clue may lie in the structure of the narrative itself. After the mention of the sign (Genesis 4:15), the narrative continues with an account of Cain’s departure to the land of Nod, “east of Eden,” and his building of a city [Genesis 4:16-17]. The logic of the narrative suggests that Cain’s city is related to the sign given him by God. The parallels with texts relating to the cities of refuge...suggest that Cain’s sign may have been the safety he found in the building of a city. His city was a sign of his divine protection from anyone “who found him.” Like the cities of refuge, Cain’s city protected him from further bloodshed...The subsequent narrative gives further evidence of the link between Cain’s sign and the cities of refuge. Still in Lamech’s day, Cain’s city is portrayed as a place of refuge for the “manslayer” [Genesis 4:24]...Hence, within the narrative’s own logic, Cain’s city may be viewed as a “city of refuge” provided him by God as protection from blood revenge (see Deuteronomy 19:11-13). The broader importance the author attaches to the “city” Cain builds can be seen in the rest of the chapter. There one finds a detailed description of the progress and development of that city. In most respects the narrative is told from a positive perspective on city life. (Tremper Longman III [b. 1952] and David E. Garland [b. 1947], Genesis ~ Leviticus (Expositor’s Bible Commentary), 102-03)
Of the many proposals as to Cain’s mark, one has been deemed unequivocally wrong (both morally and exegetically): that Cain is given dark skin. Paul J. Kissling (b. 1957) prefaces:
In the history of interpretation the mark of Cain has sometimes been assumed to be black skin. Since black-skinned people were enslaved in large numbers, it was assumed that they must be under God’s judgment. This perplexing misreading warns us of the potential for the Bible to be abused to support whatever oppressive social practice we are guilty of. This reading makes no sense of the narrative. There is no reason to believe that the mark of Cain was some genetic change which affected future generations even if we assume it was a physical mark and not a sign. Even if it was some genetic change, it was presumably wiped out in the Flood [Genesis 6:1-8:22]. (Kissling, Genesis, Volume 1 (College Press NIV Commentary), 228)
The theory took wings in antebellum America. David M. Goldenberg (b. 1947) chronicles:
Several authors in antebellum America refer to a then-current idea that Cain was smitten with dark skin as punishment for killing his brother, Abel. To some, this was the unspecified “mark” that God put on Cain “so that no one who found him would kill him” (Genesis 4:15). David Walker [1785-1830], an African American writing in 1829, reflects this view common at the time when he says, “Some ignorant creatures hesitate not to tell us that we (the blacks) are the seed of Cain..and that God put a dark stain upon us, that we might be known as their slaves!!!” The black mark of Cain, although far less common than the curse of Ham, is nevertheless found among a number of antebellum writers from 1733 onward. Phillis Wheatley [1753-1784], the African American poet, in 1773 recorded this belief in verse: “Remember Christian, Negroes black as Cain/May be refined, and join the angelic train.” (Goldenberg, The Curse of Ham: Race and Slavery in Early Judaism, Christianity, and Islam, 178)
Colin Kidd (b. 1964) informs:
For many commentators, the mark of Cain...portended a...particular racial significance. Some, such as the author of Clearer light, an anonymous English tract of 1874 which dealt, among other things, with the problems of race in the scriptures, claimed that Cain was the primal ancestor of all black people: the mark upon Cain should be read as a racial transformation which included changes to the texture of his hair and the blackening of his skin. This author also maintained that at this time Adam and Eve had no other surviving children but, even if there had been, it would have been extremely unlikely that Cain had gone on to marry any of his sisters, not least because they would have been reluctant to marry their brother’s murderer. Therefore the compelling conclusion was that there had been two distinct racial creations of mankind, one distinct from Adam and Eve into whose body Cain had married...By contrast, John Overton (1764-1838), the English genealogist of Christ, had identified Cain as the father of the Chinese race, a people whose very high antiquity suggested that in their east Asian remoteness they had escaped the Deluge which had engulfed the rest of the known world in the age of Noah. This line persisted later in the nineteenth century in the influential work of Dominick McCausland [1806-1873]...Champions of black pride transformed the curse of Cain...In particular, the black nationalist leader Marcus Garvey (1887-1940) inverted the white racist version of the mark of Cain. Garvey argued that Adam and Eve had been black as had their sons Cain and Abel. The subsequent whiteness of Cain and his descendants – down to modern Europeans – was a punishment for sin. (Kidd, The Forging of Races: Race and Scripture in the Protestant Atlantic World, 1600-2000, 34-35)
Though it gained traction in North America, the theory originated in the Rabbinic writings and gained prominence in Europe. David M. Goldenberg (b. 1947) archives:
The Curse of Cain did not originate on America soil. A curse of blackness on Cain, from whom the Blacks are descended, is often noted in European literature of the seventeenth to nineteenth century. In England Thomas Peyton [1595-1626] referred to the black African as “the cursed descendant of Cain and the devil” in his The Glasse of Time published in 1620, and in 1785 Paul Erdmann Isert [1756-1789] more expansively recorded the view that the Black’s skin color “originated with Cain, the murderer of his brother, whose family were destined to have the black colour as a punishment.” In France the Curse is mentioned in a 1733 Dissertation sur l’origine des nègres et des américains, and is recorded by Jean-Baptiste Labat [1663-1738], the Dominican missionary and also by Nicolas Bergier [1718-1790] in his Dictionnaire Théologique in 1789. It is also found in the seventeenth- and eighteenth-century Portuguese empire. (Goldenberg, The Curse of Ham: Race and Slavery in Early Judaism, Christianity, and Islam, 178-79)
The connection between race and Cain’s mark have been summarily discarded. C. Eric Lincoln (1924-2000) rejects:
Nowhere do the Scriptures state or even imply a divine intention to isolate Blacks from the dozens of races and ethnic group by relating them and them only to Cain in the Genesis story. The absurdity is further confounded because, according to Genesis, God put the mark on Cain to protect him rather than to set him up as a target (Genesis 4:15). (Lincoln, Race, Religion, and the Continuing American Dilemma, 150)
Miguel A. De La Torre (b. 1958) elucidates:
A disturbing interpretation concerning Cain’s mark is its association with blackness. According to rabbinical tradition, Cain’s mark was him becoming black. Black people, as descendants of Cain’s line, became the children of sin and murder. But such a conclusion must assume that Cain was white before he was cursed with blackness. This view is not limited to the rabbinical text, but also becomes the religious foundation of white supremacy. Cain’s mark came to mean that servitude was the consequence of making Cain black—hence justifying slavery. If Cain was originally white, then so too were his parents, Adam and Eve; and since they were created in the image of God [Genesis 1:26], then God is also white. But...if God used the best soil to create Adam, and the richer the soil the blacker it is, would it not be reasonable to assume that Adam’s skin would resemble the ingredient used? So if Adam and Eve were black, as were their children Cain and Abel, then could not the mark just as easily be that God made Cain white? Obviously, we have no idea what the color of the first humans was, nor is it important. The biblical text is silent on this topic. It only remains important to those wishing to justify the supremacy of their own race. White supremacists have read their social context into the text and assumed the first humans were white. (De La Torre, Genesis: Belief: A Theological Commentary on the Bible, 98-99)
In making the mark of Cain about race, sin is compounded.

The exact nature of the mark of Cain will have to remain a question mark. Claus Westermann (1909-2000) concludes:

I agree with those scholars who refuse to give any answer to this question. This refusal can be justified; we are dealing here with a primeval narrative. This means in the present case that the narrator is dealing with an event that is beyond the present, where things happen differently from the world of time with which we are familiar. He did not mean a mark familiar and demonstrable to his contemporaries; he had no interest at all how this mark was to be presented. It has meaning only in the context which the narrative intends to describe. We must acknowledge that even the narrator himself had no definite idea of the form of the sign. (Westermann, Genesis 1-11 (Continental Commentary), 314)
Edwin M. Good (b. 1928) agrees:
What was the “mark of Qayin” [Genesis 4:15]? No one knows; I certainly do not, nor do I wish to. “Mark” often means a sign of something, sometimes a miraculous portent, sometimes merely a banner. And a sign or mark is as close as we will ever get. It seems another instance where the storytellers portray Yahweh as improvising, responding with an on-the-spot solution to a problem he had not previously considered. In fact, Yahweh does not say that the mark will prevent Qayin from being killed, only that if he is killed, vengeance will be sevenfold. (Good, Genesis 1-11: Tales of the Earliest World, 53)
Whatever the sign it serves multiple purposes. Victor P. Hamilton (b. 1952) catalogs:
God not only says something, he does something—he puts a mark (’ôt) on Cain. Unfortunately, we do not know exactly what this mark was or where it was placed. We do know that the ’ôt can function in three ways. First, it can be a sign of proof or evidence of God’s power (Exodus 7:3, the plagues; Exodus 4:8, 9, 17, 28, 30, signs intended to show that God has sent Moses to Egypt and that the Israelites should believe in him). Second, it can be a symbol, suggesting something else by virtue of resemblance or conventional association. Thus, Ezekiel’s sun-dried brick with a relief drawing of Jerusalem under siege is a “sign” for the house of Israel (Ezekiel 4:3). This function of sign is common with the prophets. Third, it can be a sign of cognition, awakening knowledge of something in the observer. This kind of sign includes mnemonic signs (e.g., the rainbow after the Flood, Genesis 9:12, 13, 17; the eating of unleavened bread, Exodus 13:9) and identity signs, as here. The sign identifies Cain as one who is especially protected by God. Parallels to this function of sign are Exodus 12:13 (the blood on the doors at Passover which identifies the occupants); Genesis 1:14 (the heavenly lights which identify time periods); Numbers 2:2 (the banners in the Israelite camp which identify the various families); Joshua 2:12 (the sign which identifies Rahab’s house). (Hamilton, The Book of Genesis, Chapters 1-17 (New International Commentary on the Old Testament Series), 234-35)
Whatever its nature, the mark of Cain serves its purpose: Cain is not murdered. His line continues and his family thrives (Genesis 4:17-24). Cain is a marked man. But he is marked for life, not death. And he is marked as such for life.

How do you think that the mark of Cain manifested itself? Does the institution of the sign indicate that Cain’s fears are justified? Who might kill Cain? Why does Cain need a sign; is God’s word insufficient? With the population presumably small, would God’s edict not be public knowledge? What is the purpose of the mark of Cain; is the mark more to deter potential assailants or embolden Cain? What is the sign’s modern parallel; is the tattoo a fair comparison? Were you God, where would you place Cain’s sign? Does it matter what the mark is; would knowing its nature change the way the text is read? Were you Cain, what safeguard would you want to put your fears at ease? Does the mark of Cain represent justice; should God have spared Cain’s life? Given the choice, would you pick exile or death? Does the act of murder always stay with the murderer?

The mark of Cain has taken on a negative connotation through the centuries. Andrew Willet (1562-1621) typifies:

“God set a mark upon Cain [Genesis 4:15],” but not, as some read, that God made Cain to be a sign or mark. Rather, God set some visible mark upon Cain, whether it was a horrible trembling and shaking of the whole body...or an exceeding shame and confusion, in that he ran from place to place to hide himself; or some visible mark set upon his face, as Nicholas of Lyra [1270-1349] thinks. (Some Hebrews think it was a horn on his forehead; some, a letter; some, that a dog led him about; but these are human imaginings.) Certainly, whatever it was, it was a sign of God’s wrath and not, as Josephus [37-100] thinks, a token that God was appeased by Cain’s sacrifice and forgave the punishment of fratricide: for if God did not accept this sacrifice before, how much less would he after? (John L. Thompson [b. 1952], Genesis 1-11 (Reformation Commentary on Scripture), 204)
Robert Alter (b. 1935) corrects:
A mark. It is of course a mark of protection, not a stigma as the English idiom, “mark of Cain,” suggests. (Alter,Genesis: Translation and Commentary, 18)
Though the mark protects Cain (Genesis 4:15), it represents a divine balance of grace and judgment. There are consequences to Cain’s actions. But there is also mercy. John Barth (b. 1930) quips:
A completely ambivalent mark. Nobody can touch you, but everybody sure does know you’re a criminal. (Bill Moyers [b. 1934], Genesis: A Living Conversation, 77)
Victor P. Hamilton (b. 1952) pronounces:
We hear in the narrative the voice of both law and grace. Sin cannot be ignored and justified. Cain must pay a penalty for his actions. But the God who pronounces the sentence also makes available to the criminal his protection and concern that he too not become a victim of violence. Cain is banned and blessed. He is a marked man, in a positive sense. He leaves God’s presence but not God’s protection. What God would later say about Mount Sinai—“whoever touches the mountain shall be put to death” (Exodus 19:12)—he first said about Cain. (Hamilton, The Book of Genesis, Chapters 1-17 (New International Commentary on the Old Testament Series), 235)
A. Samuel Kimball (b. 1959) scrutinizes:
The sign both condemns him as a murderer and protects him from being murdered in turn; it blesses him with freedom from the very aggression he has directed against his brother. By virtue of the sign God places over Cain’s being, Cain lives as a witness to the fact that the gift of life is, in Jacques Derrida [1930-2004]’s terms, a gift of death. In his person he embodies the message that there can be no pure blessing, no pure birthright, that there can be no life that does not entail the sacrifice of other life, and that whatever blessing can come to pass must be measured against the lost futures which, by definition are beyond imagination. In short, he incarnates twice over the divided nature of all hailing: the hailing by which a (potential) subject is interpellated either into or out of existence; and the hailing by which each living person nevertheless bears the trace of the other life or lives that might have been interpellated into being if this person had not. (Kimball, The Infanticidal Logic of Evolution and Culture, 167)
Like his father, Adam (Genesis 3:24), the son is exiled (Genesis 4:12, 14). In both cases, there is also a tangible sign left as a reminder. Gordon J. Wenham (b. 1943) connects:
As the clothing given to Adam and Eve after the fall (Genesis 3:21) served to remind them of their sin and God’s mercy, so does the mark placed on Cain: “As a protective device against potential enemies it may stay death; in that sense, the anticipated punishment is softened. But at the same time it serves as a constant reminder of Cain’s banishment, his isolation from other people” (George W. Coats [1936-2006]). (Wenham, Genesis 1-15 (Word Biblical Commentary), 65)
John H. Walton (b. 1952) concurs:
In Genesis 4:15, the provision of a sign/mark treats Cain comparably to how his parents were treated. The mark placed on Cain plays a parallel role in this narrative to the garments provided for Adam and Eve in Genesis 3:21. These acts of grace serve as God’s protective provision for the new environment. In both cases it is God’s response to their recognition of the vulnerability that resulted from their offense (Adam and Eve had used fig leaves to try to cover themselves [Genesis 3:7]; Cain complained that he would be killed [Genesis 4:14]). Just as it did not matter where God got the animal skin or what it looked like [Genesis 3:21], it is of little importance what the sign is like and how it functions. In both cases the importance of the gift is in the One who gave it. (Walton, Genesis (NIV Application Commentary), 265-66)
Ronald Youngblood (b. 1931) refocuses:
Although we cannot be sure of the details, we can certainly marvel that the Lord would promise to protect so violent a man as Cain. (Youngblood, The Book of Genesis: An Introductory Commentary, 65)
God limits the death toll. Richard D. Nelson (b. 1945) comments:
The theme that humans make bad decisions that have a potential to do great harm will reappear in the stories of Cain (Genesis 4:1-16), the prelude to the flood (Genesis 6:1-8) and Babel (Genesis 11:1-9). Dangerous human potential will again need to be controlled, by a mark on Cain [Genesis 4:15], by limits on human life span [Genesis 6:3], and by language confusion [Genesis 11:7]. (Nelson, From Eden to Babel: An Adventure in Bible Study, 18)
God’s limiting humanity’s destructiveness becomes a pattern. Wolfhart Pannenberg (b. 1928) detects:
In the paradise story death is the penalty for eating the forbidden fruit [Genesis 2:17], but the entry of death is delayed, so that what we now have is a limited life span. Similarly Cain, after murdering his brother, is protected though his life forfeited (Genesis 4:15). The biblical history offers a series of examples of God’s limiting the destructive results of the sins of his people. In view of the universality of sin, the rareness of manifest outbreaks of evil is by no means self-evident. It is the consequence of God’s gracious sparing and protecting, and human ingratitude for this in the form of taking for granted the good things that happen is yet another expression of sin. (Pannenberg, Systematic Theology, Volume 2, 238)
God’s continual care for sinning humans stands in stark contrast to other ancient deities. Nahum M. Sarna (1923-2005) contrasts:
The Babylonians believed that when a man sinned his god abandoned him, allowing demons to enter his body. Although Cain was a murderer, God did not desert him but protected him with his sign as he wandered [Genesis 4:15]. Spilling Abel’s blood on the ground caused it to be cursed and all growth stopped [Genesis 4:11-12], as in the Ugaritic Tale of Aqhat,...15th-14th centuries B.C., when the goddess Anat had young Prince Aqhat slain in order to have his strong bow: “...through his death...the [fr]uits of summer are withered, the ear [in] its husk...Blasted are the buds.” In Aqhat’s tale, his sister Paghat swore, “I’ll slay the slayer of my brother, [Destroy] the [de]stroyer of my [si]bling.” Cain’s divine protection was a Biblical indictment against such blood feuds in which a family or tribe member sought to avenge the death of a kinsman. (Ada Feyerick [b. 1928], Genesis: World of Myths and Patriarchs, 67)
Perhaps the mark of Cain is left ambiguous in part to keep the focus in its proper place: on God’s activity. Gerhard Von Rad (1901-1971) expounds:
The narrative surprisingly does not conclude with this picture of the condemned murderer. Indeed, one must say that only now does it reach its most important point: Cain does not have the last word in this story, but rather God, who now places Cain’s forfeited life under strict protection. Yahweh obviously placed the sign on Cain’s body [Genesis 4:15]; the narrator appears to be thinking of a tattoo or something similar. This sign, however, is not to disgrace him but to refer to that mysterious protective relationship in which Cain would henceforth be held by God. The conclusion of the story, according to which Cain then goes forth “away from the presence of the Lord [Genesis 4:16],” completely sharpens the riddle of his future existence: because of his murder he is cursed by separation from God and yet incomprehensibly guarded and supported by God’s protection. Even his life belongs to God, and he does not abandon it. (Von Rad, Genesis: A Commentary (Old Testament Library), 107)
The mark of Cain is far from a curse; it serves to safeguard the murderer’s life. It is not punitive, but rather protective. Leon R. Kass (b. 1939) remarks:
The mark of Cain—wrongly regarded as the sign of murderous guilt—is, in fact, meant to protect Cain’s life in the wilderness, and to obviate the need for settled defense [Genesis 4:15]. As a result of this solicitous speech, Cain may at this moment glimpse the difference between a god to whom one sacrifices vegetables and the God who takes notice of, and who is outraged by, bloodshed (and who, at least for now, provides even for murderers). But moved more by dread than by reverence, Cain does not draw the most pious conclusion. Reassured but only temporarily, Cain sets out on his travels [Genesis 4:16]. (Kass, The Beginning of Wisdom: Reading Genesis, 144)
W. Sibley Towner (b. 1933) adds:
The act of grace occurs. God puts the mark on Cain, the mark of both guilt and protection [Genesis 4:15]. It will ward off anyone who would take vengeance on Cain. Anyone who would snap the link between the Eden of the past and the Eden of the future, or who would cut off human evolution before it can begin will be warned and deterred. (Towner, Genesis (Westminster Bible Companion), 64)
The sign’s positive attributes can be seen in the term for the marker. Thomas L. Brodie (b. 1940) studies:
Within the context of the close-knit fabric of Genesis, the word “sign” picks up one of the threads of creation—the lights in the heavens, which were “signs” (Genesis 1:14)—and “sign” links up also with the later sign in the heavens, the covenant rainbow (Genesis 9:13). As the sign of the rainbow moved beyond sin, indicating peace, so, in some way, did the sign on Cain; it did not allow sin to be the final word. Thus the creational theme, already noticed in Cain’s birth [Genesis 4:1], now continues. God is giving Cain a further element of creation, some form of second birth...In later centuries this positive sign was turned into something negative—“the mark of Cain,” a way of identifying an alleged criminal. But the original idea was positive, and it contained an implicit protest against blood-feud—the practice, found especially around the Mediterranean, of revenge through death, thus provoking at times a cycle of avenging deaths. (Brodie, Genesis as Dialogue: A Literary, Historical, and Theological Commentary, 154)
God is and has always been gracious. Donald E. Gowan (b. 1929) proclaims:
It was not the New Testament that first taught that God loves the unlovable. Cain is scarcely an endearing character, moving as he has from anger to violence to resentment, yet God’s judgment upon him is mixed with mercy (Genesis 4:15). It is not God’s intention that one killing should produce more. He uses the oath of a family avenger of blood (Judges 8:18-21; II Samuel 2:22-23, 3:26-30; II Kings 14:5), but here as a guardian who intends to prevent bloodshed rather than as an executioner. We are given not one clue as to the nature of the mark, and much time has been wasted on pure speculation as to what it might have been; indeed, since nothing suggests that anyone but Cain has ever borne it, the question is completely irrelevant. Its only meaning as the story is told is as a sign of God’s grace, even grace towards the archetype of violent mistreatment of one’s brothers and sisters. Here as elsewhere we are assured that even in the midst of God’s just judgment of our sins he intervenes to save us from the worst possible consequences we might bring upon ourselves. (Gowan, Genesis 1-11: From Eden to Babel (International Theological Commentary), 72)
Derek Kidner (1913-2008) praises:
God’s concern for the innocent (Genesis 4:10) is matched only by His care for the sinner. Even the querulous prayer of Cain had contained a germ of entreaty; God’s answering pledge together with His mark or sign (the same word as in Genesis 9:13, 17:11) – not a stigma but a safe-conduct – is almost a covenant, making Him virtually Cain’s gō’ēl or protector; cf. II Samuel 14:14b...It is the utmost that mercy can do for the unrepentant. (Kidner, Genesis (Tyndale Old Testament Commentaries), 76)
Though exiled (Genesis 4:12), God’s marks forever attaches the murderer to the deity. Celia Brewer Marshall (b. 1954) avows:
God marks Cain as God’s own forever. It is a permanent mark of God’s guardianship and custody. While hardly a badge of honor, it is incorrect to read the “mark of Cain” as folklore has mistakenly interpreted it. It is neither a bull’s-eye for hit men nor a brand for shame. The mark is a sign of God’s continued protection and mercy, like the clothing of Genesis 3:21. God is in effect saying, “This mark tells the world you are mine. If anyone comes after you, he’ll have to answer to me.” (Marshall, Genesis (Interpretation Bible Studies), 25)
André LaCocque (b. 1927) theorizes:
Everywhere he goes Cain is carrying the mark of God. Not a tattoo; not a branded stamp; not a tribal emblem (at most, something like Zeus’s aegis); but rather perhaps, just his humanity, in the image of God. An interesting Misrashic reading of Genesis 4:15 (in Genesis Rabbah 22) has God setting Cain in person as a sign of warning not to kill him or as a sign addressed to all people willing to repent. From a syntactical point of view, this Midrashic translation is not without foundation; the Wilhelm Gesenius [1786-1842]-Emil Kautzsch [1841-1910]-A.E. Cowley [1861-1931] grammar refers to the construction of Isaiah 5:20. (LaCocque, Onslaught against Innocence: Cain, Abel, and the Yahwist, 67-68)
Helmut Thielicke (1908-1986) sermonizes:
Even Cain is not altogether forsaken in the land of Nod. Even about him God throws a circle of protection and put upon him a sign, the mark of Cain, which makes him taboo [Genesis 4:15]. Even the guilt-laden man remains God’s property. He too is given room to repent...In centuries past the judge who had condemned a murderer to death would partake of the sacrament of the Lord’s Supper with him before his execution. By doing this he was saying to him, “You poor, lost sinner, whom we are about to do to death, are nevertheless something totally different from what we human beings see in you. You are not merely a man who has been branded with the curse of society; you are still part of another, invisible order, that can grant you a grace and pardon over which we human beings have no control. You bear the mysterious mark of Cain that makes you the property of Another—just as we judges are the property of that Other and therefore stand in an ultimate solidarity with you.” (Thielicke, How the World Began: Sermons on the Creation Story, 227-28)
The sign is not named nor described. This is good. This way the sign does not detract from its own meaning: God is just yet manages to parlay the grace that the murderer did not.

Do you have positive or negative associations with the mark of Cain? Should the mark put Cain at ease or be a perpetual reminder of his sin? Where else do grace and judgment intertwine? When has a sign detracted from its own message? What other marks are you familiar with? Are you marked by God? If so, how?

“It is mercy, not justice or courage or even heroism, that alone can defeat evil.” - Peter J. Kreeft (b. 1937), The Philosophy of [J.R.R.] Tolkien [1892-1973]: The Worldview Behind the Lord of the Rings, p. 217