If we say we have no sin*, we deceive ourselves and the truth is not in us. If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. If we say that we have not sinned, we make Him a liar, and His word is not in us. (1 John 1.8-10)
*That is, that we do not have the sin nature.