Problem: In the OT, murderers were given capital punishment for their crime (Gen. 9:6; Ex. 21:12). Yet Cain was not only set free after murdering his brother, but he was protected from any avenger (Gen. 4:15).
Solution: There are several reasons why Cain was not executed for his capital crime. First, God had not yet established capital punishment as an instrument of human government (cf. Rom. 13:1–4). Only after violence filled the earth in the days before the flood did God say, “Whoever sheds man’s blood, By man his blood shall be shed; For in the image of God He made man” (Gen. 9:6).
Further, who would have killed Cain? Cain had just killed Abel. At this early stage only Adam and Eve were left. Surely, God would not have called upon the parents to kill their only remaining son. In view of this, God, who alone is sovereign over life and death (Deut. 32:39), personally commuted Cain’s death penalty. However, in so doing, God implied the gravity of Cain’s sin and implied he was worthy of death by declaring that “the voice of your brother’s blood cries out to Me [for vengeance] from the ground” (v. 10). Nonetheless, even Cain seemed to recognize that he was worthy of death, and he asked God for protection (v. 14). Finally, God’s promise to protect Cain from vengeance implies capital punishment would be taken on any who took Cain’s life (cf. v. 15). So, Cain’s case is the exception that proves the rule, and by no means does it argue against capital punishment as established by God (see comments on John 8:3–11).
