John Piper reflects on the nature of sin and Psalm 51, as David laments and repents of his adultery with Bathsheba and his murder of Uriah. David confesses at least five ways that his sin is extremely serious.
1. He says that he can’t get the sin out of his mind.
It is blazoned on his conscience. Verse 3:
2. He says that his exceeding sinfulness is only against God.
For I know my transgressions, and my sin is ever before me.
Nathan had said David despised God and scorned his word. So David says in verse 4,
3. He doesn't justify himself.
Against you, you only, have I sinned and done what is evil in your sight.
David vindicates God, not himself. There is no self-justification. No defense. No escape. Verse 4:
4. He intensifies his guilt by drawing attention to his inborn corruption.
…so that you may be justified in your words and blameless in your judgment.
5. He admits that he sinned not just against external law but against God’s merciful light in his heart.
Behold, I was brought forth in iniquity, and in sin did my mother conceive me.
Behold, you delight in truth in the inward being, and you teach me wisdom in the secret heart.
From the conclusion:
God had been his teacher. God had made him wise. David had done so many wise things. And then sin got the upper hand. For David, this made it all the worse. “I have been blessed with so much knowledge and so much wisdom. O how deep must be my depravity that it could sin against so much light.”
So in those five ways at least David joins the prophet Nathan and God in condemning his sin and confessing the depths of his corruption.
Excerpted and adapted from the sermon "A Broken and Contrite Heart God Will Not Despise."