How to answer "I know that I know that I know"?

[Angrboda]

The best way to help him is to study the bible and show him that he isn't living acording to Gods word. Before you all jump on me , the OP really is interested to help his friend , he may not be able to change his belief , but at least he can use his belief to make him change his way.

I agree with this. Your friend has a heavy bias in favor of his views about God. It will be nothing but a futile battle trying to attack his beliefs. Better to use his religious beliefs and the bible to encourage him that God would want him to live more responsibly. Doesn't the parable of the three servants say as much? I think fighting against his belief will simply encourage further pious behavior. Work with the grain, not against it.