Psalm 51 is one of the most well-known psalms because it is the response of a broken David following his affair with Bathsheba. It is the heartfelt pleas of a lowly man, humbled by God because of his sin but it can be helpful to study for any believer struggling with any sin, not just adultery. It lays out a helpful pattern for response to sin. To begin with, it is helpful but sobering to realize that David was a “man after God's own heart” who was coming off intense spiritual experiences, with the Living God, when he failed so miserably as to commit murder and adultery because of his selfish lusts. The remaining sin/power of the flesh is so great, even in believers that anyone is susceptible to it's lure, which should lead us to extreme care of our souls.
When we sin, which is inevitable, we can follow the example laid down by David in Psalm 51. Possibly the most important part of the Psalm is the beginning, when David does not try to “get his act together” and then come before God. He comes just as he is, and he appeal for forgiveness is not based on his own merits but the character of God. “Have mercy on me, O God, according to your steadfast love; according to your abundant mercy blot out my transgressions. v2” David's worth is not even on his mind, in fact he's well aware of how unworthy he is, “For I know my transgressions and my sin is ever before me. v3”
[6]Behold, you delight in truth in the inward being,
and you teach me wisdom in the secret heart.
[7]Purge me with hyssop, and I shall be clean;
wash me, and I shall be whiter than snow.
[8]Let me hear joy and gladness;
let the bones that you have broken rejoice.
[9]Hide your face from my sins,
and blot out all my iniquities.
[10]Create in me a clean heart, O God,
and renew a right spirit within me.
[11]Cast me not away from your presence,
and take not your Holy Spirit from me.
[12]Restore to me the joy of your salvation,
and uphold me with a willing spirit.
[13]Then I will teach transgressors your ways,
and sinners will return to you.
This section is vitally important to understanding our motivations for repentance. The emphasis is placed on the work of God in our lives and our primary motivation for asking God's forgiveness is a renewed and deep relationship with God. As believers our sin no longer condemns us before God because of the imputed righteousness of Christ but the effect of our sin is a change in our personal relationship with God. Paul shows us that we can “grieve the Holy Spirit” (Eph. 4:30) and “the Lord disciplines those that He loves” (Heb. 12). Just as an earthly father still loves his children when they disobey, our heavenly father continues in love and it is because of this love that He does not allow us to persist in our sins.
Therefore our main motivation is God turning His face back towards us and away from our sins but there are secondary motivations as well. In verse 10 David cries out for God to work within him for spiritual change. This same heart that was after God now needs to be made clean, but note that it is not David making it clean by his efforts or personal holiness but rather God's work in us that leads to a “right spirit”. Another attitude to be craved by believers is a credible witness to believers, as shown in verse 13. When God shows his faithfulness to us, we should use this as a way to witness to others and he promises to return sinners to Himself. We should crave the type of life that serves as a witness to non-believers but we can always extol the faithfulness of God.
Our confession of sin is not for self-abasement or flagellation but to return us to the joy that we have in the salvation of God. Verses 8 and 12 both speak of the joy that needs to follow the forgiveness of our sins because we can trust the promises of our faithful God that He will forgive our sins if we confess them. (1 John 1:9). This ties in to the final section of the Psalm:
[14]Deliver me from bloodguiltiness, O God,
O God of my salvation, and my tongue will sing aloud of your righteousness.
[15]O Lord, open my lips,
and my mouth will declare your praise.
[16]For you will not delight in sacrifice, or I would give it;
you will not be pleased with a burnt offering.
[17]The sacrifices of God are a broken spirit;
a broken and contrite heart, O God, you will not despise.
Our response to this forgiveness should always be the worship of God. We should see God's righteousness and forgiveness and “sing aloud”. The ESV Study Bible says, “The person who has used this psalm to confess his sins and to receive God's assurance of pardon is the one who can genuinely worship the gracious God of the covenant.”
David then again reminds us that God doesn't delight in our “sacrifices” aka our works but rather responds to our humility. He opposes the proud but gives grace to the humble. We cannot earn the forgiveness or grace but it is a free gift of God. He will not despise when we come humbly before him, admitting our failure and acknowledging our dependence on Him to grow, asking for His Spirit to change us for His glory and to being sinners to Him.