Psalms 51-55: A Matter of the Heart

When is our cry to God most honest?  When we are crying out for help when we are under attack, or when we are crying out in desperation for mercy because of our own hearts?  David's cries to God are the most poignant when he goes to God after being confronted by the prophet Nathan for committing adultery with Bathsheba.  His sin and his treachery against Uriah was great, but David realized that he had committed a greater sin against God.  He could not get it out of his mind. The prospect of being separated from God was more than he could bear. None of his cries to God, even when he was being pursued to the death by king Saul, were as full of pain as this cry from his heart.
Have mercy on me, O God, according to your unfailing love;
according to your great compassion blot out my transgressions.
Wash away all my iniquity and cleanse me from my sin.
For I know my transgressions, and my sin is always before me.
Against you, you only, have I sinned and done what is evil in your sight,  - Ps 51:1-4

In the end, all of our sins are against God, and only he can restore us.