One of the penitential psalms, Psalm 51 was written by David after he was confronted by the prophet Nathan. Nathan declared that David had grievously sinned against God in the taking of Bathsheba to be his wife and in the murder of her husband, Uriah.
It’s important to see the anguish and heartfelt remorse expressed by David, but we must also understand that repentance of the heart is the work of God the Holy Spirit. David is repentant because of the influence of the Holy Spirit upon him. Not only that, but as he writes this prayer, he is writing it under the inspiration of the Holy Spirit. The Holy Spirit demonstrates in Psalm 51 how He produces repentance in our hearts. Keep this in mind as we look at the psalm.
Psalm 51 begins, “Have mercy on me, O God, according to your steadfast love; according to your abundant mercy blot out my transgressions” (v. 1). Here we see an element that is fundamental to repentance. Usually, when a person becomes aware of his sin and turns from it, he casts himself on the mercy of God. The first fruit of authentic repentance is the recognition of our profound need for mercy. David does not ask God for justice. He knows that if God were to deal with him according to justice, he would be immediately destroyed. As a result, David begins his confession with a plea for mercy.
When David pleads with God to blot out his transgressions, he’s asking God to remove the stain from his soul, to cover his unrighteousness, and to cleanse him from the sin that is now a permanent part of his life. So he says, “Wash me thoroughly from my iniquity, and cleanse me from my sin!” (v. 2).
The ideas of forgiveness and cleansing are related, but they are not the same thing. In the New Testament, the Apostle John writes, “If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness” (1 John 1:9). In a spirit of repentance, we go before God and confess our sins, asking not only for the pardon, but also for the strength to refrain from doing that sin anymore. As David does in this psalm, we ask that our inclination to wickedness be eliminated.