1 John 3:11-15

This is the teaching you have heard from the beginning: We must love each other. Do not be like Cain who belonged to the Evil One and killed his brother. And why did he kill him? Because the things Cain did were evil, and the things his brother did were good. Brothers and sisters, do not be surprised when the people of the world hate you. We know we have left death and have come into life because we love each other. Whoever does not love is still dead. Everyone who hates a brother or sister is a murderer, and you know that no murderers have eternal life in them.