The Unsung Hero (2014) Why did Cain kill his brother? The Lord... Why did Cain kill his brother? The Lord warned, "If you do what is right, will you not be accepted? But if not, sin crouches at the door." Instead of taking up the battle against sin, Cain took up the battle against his brother Abel. On the other hand, Abel did not sin. Though it cost him his life, this unsung hero recognized that the battle wasn't with his brother, but with sin. This concept returns in the book of Ephesians. "For we wrestle not against flesh and blood, but against [...] spiritual wickedness in high places" (6:12). In other words, s truggle with sin isn't struggle with other people, or even yourself. Instead, the battle with sin is a fight against spiritual forces of evil. This battle is won by Jesus Christ when you give yourself totally to him . This raises two questions. First, how do you feel about your sin--if there be such? Do you make arguments in favor of si...