Have mercy on me, O God,
according to your steadfast love;
according to your abundant mercy
blot out my transgressions.
Wash me thoroughly from my iniquity,
and cleanse me from my sin!
— Psalm 51:1-2 ESV

Read the whole psalm here. 

David writes this psalm after he is confronted by Nathan about his sin with Bathsheba, and it is a song of repentance. David, who was supposed to be a man after God's own heart, had committed adultery, deceit, and murder. God, through Nathan, called him out and this psalm is a result of the conviction that David feels. This psalm can be divided into four stages of David's repentance to God. Verses 1-5 describe David simply asking for forgiveness and acknowledging that he has sinned against God, and that God is just in any judgement or wrath. Verses 6-13 show David asking for a renewal and restoration of God's presence in his life. Verses 14-17 describe examples of public worship: sing aloud, declare your praise, sacrifice. David ends the psalm by showing the relationship between repentance and the condition of God's people, Zion.

Repentance should be one of the most important parts of the Christian life, and David's example is the best we can follow. As Christians, we are already fully forgiven by Jesus's sacrifice, for all of the sins we have committed in the past, and for all of the sins we have yet to commit. However, we are still called to live lives of repentance. 1 John 1 describes walking in the light just as God is in the light, and that the confession of our sin is what allows us to walk in freedom and righteousness.

Even though we are already fully forgiven, repentance should be a part of our daily prayer life due to our sinful human nature. We should follow David's example and ask for mercy, ask for forgiveness, and ask for a new anointing of the Holy Spirit on our lives. And this prayer should then lead us into gratitude and worship because of the forgiveness and freedom the God gives us, and we should rejoice that even though we sin, "he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness" (1 John 1:9).

pray

God,
You are such a good father. Thank you for the grace that you have poured out on us, your children. I ask that you would continue to show us grace and mercy, and that you would continue to pour your Spirit out on us, so that we may bear good fruit and live in the freedom that you have promised us. "O Lord, open my lips, and my mouth will declare your praise." We love you, God. Amen.

- Hunter MacInnis