My dear children, I write this to you so that you will not sin. But if anybody does sin, we have an advocate with the Father—Jesus Christ, the Righteous One. He is the atoning sacrifice for our sins, and not only for ours but also for the sins of the whole world. We know that we have come to know him if we keep his commands. 4 Whoever says, “I know him,” but does not do what he commands is a liar, and the truth is not in that person. 5 But if anyone obeys his word, love for God[a] is truly made complete in them. This is how we know we are in him: 6 Whoever claims to live in him must live as Jesus did. 7 Dear friends, I am not writing you a new command but an old one, which you have had since the beginning. This old command is the message you have heard. 8 Yet I am writing you a new command; its truth is seen in him and in you, because the darkness is passing and the true light is already shining. 9 Anyone who claims to be in the light but hates a brother or sister[b] is still in the darkness. 10 Anyone who loves their brother and sister[c] lives in the light, and there is nothing in them to make them stumble.