In Genesis 4, the Bible records the first murder. Cain murders his brother Abel.
The tragedy of the story is compounded because Cain was Eve’s firstborn son, a blessing of God. As Eve says, “I have gotten a man with the help of the Lord” (Gen 4:1). This child was Cain, whose name plays on the Hebrew word which is translated by the phrase “I have gotten.” God blessed Eve with a child, and she got him.
But Cain sinned. He murdered. And so as the Lord had exiled Adam and Eve from the garden in Eden, now he would drive Cain away from the land of Eden itself (Gen 2:8; 3:23–24; 4:16).
God also drove Cain away from the ground. As a worker of the ground in the land of Eden, Cain’s punishment felt unbearable.
So he complains, “My punishment is greater than I can bear” (Gen 4:13).
And God hears him.
“Then the Lord said to him, ‘Not so! If anyone kills Cain, vengeance shall be taken on him sevenfold.’ And the Lord put a mark on Cain, lest any who found him should attack him” (Gen 4:15).
God places “a mark on Cain.” And here we enter into a potentially confusing part of the story. Just what is this mark that the Lord put on Cain?
Many have ventured to answer the question. Some say it was a physical mark on the forehead (Ezek 9:4). Others think it might refer to Cain’s appearance more generally. Still others see it as a mark that leads others to repentance.
Yet attempting to find the answer by a physical characteristic, I believe, misunderstands the meaning of the “mark” within the context of Genesis 1–5. The mark of Cain, instead, points like a sign to God’s enduring grace for all human beings.
The “Mark” in Context
Genesis 2–3 tells the story of life in the garden as well as the Fall of humankind. Genesis 4 follows these two chapters and contrasts life in Eden with life outside of Eden. For this reason, Genesis 4 helps us understand how God deals with human beings after the original sin of Adam and Eve.
Genesis 3:17 already anticipates Cain’s exile from the ground when it says, “cursed is the ground because of you.” The son of Adam then would become “ a worker of the ground” and later one who is “cursed from the ground” (Gen 4:2, 11).
Cain’s murder of Abel rebels against the blessing of God, “Be fruitful and multiply and fill the earth” (Gen 1:28). The birth of Seth, a third brother, shows that God’s promise stands (Gen 4:25–26).
And yet life in exile from Eden’s garden and so the Tree of Life (3:24) means that death spreads to all men, because all men sin. The Genealogy of Genesis 5 cements this doctrine by the refrain “and he died.” Genesis confirms the consequences of eating from the tree of the knowledge of good and evil—death (Gen 2:17).
Genesis 5:1 by its use of the phrase, “This is the book of the generations of Adam,” signals that this chapter not only harkens back to the creation of Adam but also forward to his descendants since the chapter lists a genealogy of Adam’s descendants.
For these, and many more reasons, Genesis 1–5 should be read together. So we should reasonably expect the mark of Cain to somehow relate to life in Eden’s garden as other aspects of the story do.
Within Genesis 1–5, the only other occurrence of the word “mark” is in Genesis 1:14–15, and there it is translated into English as “signs.”
The passage says:
“Let there be lights in the expanse of the heavens to separate the day from the night. And let them be for signs and for seasons, and for days and years, and let them be lights in the expanse of the heavens to give light upon the earth.”
There, the sun and moon are signs “for seasons, and for days and years” as well as those powers which “separate the day from the night.” God created the cosmic patterns to order his creation and to divide light from darkness. These powers “rule” or “govern” the day and night (Gen 1:16).
The word translated signs is the Hebrew word ’ot, and it means sign. The translation “mark” in Genesis 4:15 provides an English translation of what the translators understand the word to mean in context. And I think it’s a good translation but one that, without Hebrew knowledge, could potentially make understanding the meaning of the mark or sign more difficult than it otherwise would be.
Signs Point to Something
Signs signify, that is, they point to something. A stop sign signifies that one should stop. The Nike logo signifies a brand, a company, that makes shoes and clothing. The golden arches of McDonald’s signify that food is here. At a traffic light, green signifies go. The cosmic powers in the sky signify God’s ordering of the cosmos by the heavenly powers: sun, moon, and stars.
The bread in the Lord’s Supper signifies the body of Christ, the wine the New Covenant in his blood poured out for us.
Cain’s mark or sign signifies grace, but not forgiveness. This is true because God does not reverse the punishment of Cain but rather adds the mark to protect Cain—“lest any who found him should attack him” (Gen 4:15). This protective or preserving grace allowed Cain to head East of Eden and flourish.
In fact, the rest of the story shows how Cain’s family-line not only was protected but achieved excellence. Bible commentator Kenneth Matthews notes, “Remarkably, however, the grace of God toward Cain enables Adam’s firstborn to survive and later father an impressive lineage whose members are remembered for notable cultural achievements” (Genesis 1–11:26, 258–59).
Cain had a family and built a city (Gen 4:17). His descendants became ranchers and lived in tents (Gen 4:20). They invented and played “lyre and pipe” (Gen 4:21). They created instruments of bronze and iron (Gen 4:22). Even though his poetry was marred by sin, Lamech wrote poetry (Gen 4:23–24).
Reformed theologian Herman Bavinck explains, “Cain is driven from God’s presence because of fratricide (Gen. 4:14,16). Yet he continues to live; grace is thus given to him in place of strict justice. Cain indeed becomes the father of a tribe which sets its mind to the task of subduing the earth and begins the development of human culture (Gen. 4:15-24)” (Common Grace, 40).
The mark of Cain thus preserves life as a form of grace, preserving grace. But the grace of God does not just preserve but allows humanity to flourish. In the language of John Calvin, The Spirit distributes excellent benefits “for the common good of mankind” (Inst. 2.2.16).
Yes, But What Is the Mark Exactly?
The text of Genesis provides no physical description of the mark. No hint of it exists. My own view is the mark or sign of Cain is the Word of God that declares: “Not so! If anyone kills Cain, vengeance shall be taken on him sevenfold.” As the Word of God brought the universe into existence and ordered according to natural law, so the Word of God creates preserving grace over Cain to protect him and his progeny from death.
Even if the sign had some physical characteristic (the text does not tell us what it is), this characteristic would still signify what the sign points to: the preserving grace of God. In a similar way (but not in the exact same way), Baptism and the Lord’s Supper are physical signs of invisible grace.
While the Word of punishment remains—Cain is exiled from the ground and must go east of Eden—the Word of grace preserves Cain and his line, allowing them to flourish in various respects.
Matthews similarly comments, “Perhaps the answer is that by the “sign” God prevents the spread of bloodshed that otherwise would escalate” (Genesis 1–11:26, 278). The last two verses of Genesis 4, however, show the limits of human flourishing.
Genesis 4:25–26 says: “And Adam knew his wife again, and she bore a son and called his name Seth, for she said, “God has appointed for me another offspring instead of Abel, for Cain killed him.” To Seth also a son was born, and he called his name Enosh. At that time people began to call upon the name of the Lord.”
Another son of promise is born—through him would the head of the serpent be crushed (Gen 3:15). And through the line of Seth does true worship of God occur along with the promise.
Genesis 5 too shows the limit of human flourishing apart from faith in God. The refrain “and he died” shows the finality of the punishment of death—“in the day that you eat of it you shall surely die” (Gen 2:17). Death comes to all because all men sinned.
If the seen of the woman does not the crush of the head of the serpent, then human flourishing means little. Death comes to all. What will it profit a man to gain the world and lose his own soul (Matt 26:26).
Through the Gospel, however, all of the goodness of the created order comes into its fullness. As Herman Bavinck explains, God’s special revelation “completes all that had been from the beginning put into human nature by revelation and had been preserved and increased subsequently in the human race” (Philosophy of Revelation, 155).
The mark of Cain is God’s Word of preserving grace. Genesis 4 does not describe the physical characteristics of the mark. Instead, the Bible draws us back to the creation account in which God creates another “mark” or “sign” in which God creates the sun and moon to divide night and day, order the cosmos, and rule over day and night (Gen 1:16–18). The mark of Cain points to grace.
 Kenneth Matthews notes, “Whereas Chaps. 2–3 recount the Life of Adam and Eve inside the garden, Chap. 4 will relate a new episode in the ongoing story of the first couple’s experience—but now outside the garden” (Genesis 1–11:26, 258).