First Letter of John

Whoever is born of God doesn't commit sin, because his seed remains in him; and he can't sin, because he is born of God.

In this the children of God are revealed, and the children of the devil. Whoever doesn't do righteousness is not of God, neither is he who doesn't love his brother.

For this is the message which you heard from the beginning, that we should love one another;

unlike Cain, who was of the evil one, and killed his brother. Why did he kill him? Because his works were evil, and his brother's righteous.