The Doctor: The Sin of Morality

I would say that the greatest sinners in the world are the self-satisfied, self-contained, good moral people, who believe that, as they are, they are fit to stand in the presence of God.  Moreover, they are in reality telling God that He need never have sent His Son into the world as far as they are concerned, and that the Son need never have died upon the Cross.  There is no greater insult to God than that; but that is precisely what they are guilty of.  There is no greater sinner in the universe than the man who has never seen his need of the blood of Christ.  There is no greater sin than that – murder and adultery and fornication are nothing in comparison with it.  – D. Martyn Lloyd-Jones, Romans Vol. 4, p. 291