Question: “What was the mark that God put on Cain (Genesis 4:15)?”
Answer: After Cain killed his brother Abel, God declared to Cain, “Now you are under a curse and driven from the ground, which opened its mouth to receive your brother’s blood from your hand. When you work the ground, it will no longer yield its crops for you. You will be a restless wanderer on the earth” (Genesis 4:11-12). In response, Cain lamented, “My punishment is more than I can bear. Today you are driving me from the land, and I will be hidden from your presence; I will be a restless wanderer on the earth, and whoever finds me will kill me” (Genesis 4:13-14). God responded, “Not so; if anyone kills Cain, he will suffer vengeance seven times over.” Then the Lord put a mark on Cain so that no one who found him would kill him” (Genesis 4:15-16).
The nature of the mark on Cain has been the subject of much debate and speculation. The Hebrew word translated “mark” is ‘owth and refers to a “mark, sign, or token.” Elsewhere in the Hebrew Scriptures, ‘owth is used 79 times and is most frequently translated as “sign.” So, the Hebrew word does not identify the exact nature of the mark God put on Cain. Whatever it was, it was a sign/indicator that Cain was not to be killed. Some propose that the mark was a scar, or some kind of tattoo. Whatever the case, the precise nature of the mark is not the focus of the passage. The focus is that God would not allow people to exact vengeance against Cain. Whatever the mark on Cain was, it served this purpose.