1 John 3:11-15

For this is the message which you [believers] have heard from the beginning [of your relationship with Christ], that we should [unselfishly] love and seek the best for one another; and not be like Cain, who was of the evil one and murdered his brother [Abel]. And why did he murder him? Because Cain’s deeds were evil, and his brother’s were righteous. Do not be surprised, believers, if the world hates you. We know that we have passed out of death into Life, because we love the brothers and sisters. He who does not love remains in [spiritual] death. Everyone who hates (works against) his brother [in Christ] is [at heart] a murderer [by God’s standards]; and you know that no murderer has eternal life abiding in him. [Matt 5:21-23]