1 John 3:8-10

3:8 The one who practices sin is of the devil, because the devil has been sinning from the beginning. For this purpose the Son of God was revealed: to destroy the works of the devil. 3:9 Everyone who has been fathered by God does not practice sin, because God’s seed resides in him, and thus he is not able to sin, because he has been fathered by God. 3:10 By this the children of God and the children of the devil are revealed: Everyone who does not practice righteousness – the one who does not love his fellow Christian – is not of God.

1 John 3:12

3:12 not like Cain who was of the evil one and brutally murdered his brother. And why did he murder him? Because his deeds were evil, but his brother’s were righteous.