1 John 1:8- 9
8 If we claim to be without sin, we deceive ourselves and the truth is not in us.
9 If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness.[/QUOTE]
Can't you say "I have no sin" after you have been cleansed of ALL unrighteousness?
John is speaking of those who walk in darkness, who cannot say they have no sin (1 Jo 1:6)