If we say that we have no sin, we deceive ourselves, and the truth is not in us.
we deceive ourselves: This is John’s response to the false avowal of sinlessness. Vincent says this statement literally means, we lead ourselves astray (319). Self-deception is the worst kind of deception because it is so difficult to overcome. When one is deceived by others, the truth will often quickly overcome that deception; but when one is self-deceived, he is so involved in his own deception that truth is hard to accept. When one deceives himself by saying, "I have no sin in my life," he associates himself with those who "professing themselves to be wise, they became fools" (Romans 1:22). There is no greater fool than the self-deceived fool.