But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus Christ, his Son, cleanses us from all sin.

 1:8-10 If we say that we have no sin, we deceive ourselves and the truth is not in us. If we confess our sins, we can rely on him in his righteousness to forgive us our sins and to make us clean from all unrighteousness. 