For this is the message that you have heard from the beginning, that we should love one another. We should not be like Cain, who was of the evil one and murdered his brother. And why did he murder him? Because his own deeds were evil and his brother’s righteous. Do not be surprised, brothers, that the world hates you. We know that we have passed out of death into life, because we love the brothers. Whoever does not love abides in death. Everyone who hates his brother is a murderer, and you know that no murderer has eternal life abiding in him.
By this we know love, that he laid down his life for us, and we ought to lay down our lives for the brothers. But if anyone has the world’s goods and sees his brother in need, yet closes his heart against him, how does God’s love abide in him? Little children, let us not love in word or talk but in deed and in truth.
By this we shall know that we are of the truth and reassure our heart before him; for whenever our heart condemns us, God is greater than our heart, and he knows everything. Beloved, if our heart does not condemn us, we have confidence before God; and whatever we ask we receive from him, because we keep his commandments and do what pleases him. And this is his commandment, that we believe in the name of his Son Jesus Christ and love one another, just as he has commanded us. Whoever keeps his commandments abides in God, and God in him. And by this we know that he abides in us, by the Spirit whom he has given us.
(1 John 3:11–24)