True Belief and True Repentance
We see here how terrible it is to be a slave of sin, as Saul hasn't changed. He is not only physically asleep when David enters the camp, but spiritually dead. He feels guilty over his sin again, but makes no mention of God. True conversion is when a person goes to Christ. The Christian is not only saved from hell but from the power of sin; we don't have to obey it.