The Anatomy of Cain's Anger

Cain hated his brother Abel because his own works were evil and his brother's were righteous. He was envious of Abel, and envy is always sinful and is a characteristic of the devil. His envy led to unrighteous anger and finally murder.

Anger is a grievous sin that is an effect of the Fall, resulting in our thoughts and emotions being out of sorts. God desires for us to examine ourselves and to repent of our envy and anger toward our brothers and sisters.