This is the message he has given us to announce to you: God is light and there is no darkness in him at all. So we are lying if we say we have fellowship with God but go on living in spiritual darkness. We are not living in the truth. But if we are living in the light of God's presence, just as Christ is, then we have fellowship with each other, and the blood of Jesus, his Son, cleanses us from every sin.
If we say we have no sin, we are only fooling ourselves and refusing to accept the truth. But if we confess our sins to him, he is faithful and just to forgive us and to cleanse us from every wrong. If we claim we have not sinned, we are calling God a liar and showing that his word has no place in our hearts.