Cain was “very angry” and his countenance “fell” because “the Lord had regard for Abel and his offering” (GEN 4:4-5). The biblical text does not reveal the reason why God prefers Abel’s sacrifice to Cain’s. It clearly shows however that God, although preferring Abel’s gift, does not interrupt his dialogue with Cain. He admonishes him, reminding him of his freedom in the face of evil: man is in no way predestined to evil. Certainly, like Adam, he is tempted by the malevolent force of sin that, like a wild beast, lies in wait at the door of his heart, ready to leap on its prey. But Cain remains free in the face of sin. He can and must overcome it: “Its desire is for you, but you must master it” (GEN 4:7).
Envy and anger have the upper hand over the Lord’s warning, and so Cain attacks his own brother and kills him. As we read in the Catechism of the Catholic Church: “In the account of Abel’s murder by his brother Cain, Scripture reveals the presence of anger and envy in man, consequences of original sin, from the beginning of human history. Man has become the enemy of his fellow man”.
Brother kills brother. Like the first fratricide, every murder is a violation of the “spiritual” kinship uniting mankind in one great family, in which all share the same fundamental good: equal personal dignity. Not infrequently the kinship “of flesh and blood” is also violated; for example when threats to life arise within the relationship between parents and children, such as happens in abortion or when, in the wider context of family or kinship, euthanasia is encouraged or practiced.
At the root of every act of violence against one’s neighbor there is a concession to the “thinking” of the evil one, the one who “was a murderer from the beginning” (JN 8:44). As the Apostle John reminds us: “For this is the message which you have heard from the beginning, that we should love one another, and not be like Cain who was of the evil one and murdered his brother” (1 JN 3:11-12). Cain’s killing of his brother at the very dawn of history is thus a sad witness of how evil spreads with amazing speed: man’s revolt against God in the earthly paradise is followed by the deadly combat of man against man. – From Evangelium Vitae (1995)
