1John 1:8-10 says, "If we say that 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."
The problem believing that man can live without sin makes him believe that God is his debtor..He is so good God owes him salvation...
You beat me to it, but obviously there are many in the churches every Sunday, deceiving themselves, and worse others as well.