Psalm 51 is an exceptional model for the confession of sin. These words of David appeal to the character of God and his divine faithfulness secured in the covenant he has with his people.

The setting for this Psalm is precisely identified in the superscript as the time when the prophet Nathan came to David to confront David concerning his sin with Bathsheba and the orchestration of the murder of her husband Uriah (2 Samuel 11 and 12).

The first six verses can be outlined as follows:

1. Request for forgiveness in Psalm 51:1-2
2. Confession of the personal sins in Psalm 51:3-4 (similar to confession of known personal sins in 1 John 1:9)
3. Rationalization of God’s judgment in Psalm 51:4b
4. Confession of having a sin nature in Psalm 51:5-6 (Similar to universal sin stated in 1 John 1:8, 10)

Parallels between David’s words to Nathan, the prophet, in 2 Samuel 12 can be made with the statements and wording also used in Psalm 51. For example:

1. In 2 Samuel 12:13 David says, “I have sinned against the Lord (YHWH).” This matches David’s words in Psalm 51:4 when says in similar fashion, “Against you, you only, have I sinned and done what is evil in your sight.”
2. David uses the verb “sin” in 2 Samuel 12:13. The same Hebrew verb for sin used in 2 Samuel 12:13 is used in 7 verses of this psalm, Psalm 51:2, 3, 4, 5, 7, 9, 13. In 51:7 the word for “sin” is found in the Hebrew word translated “cleanse me” which could literally be translated “un-sin me.”)

Davd’s confidence in approaching God is immediately found in the first two verses (51:1-2) where God’s “unfailing love” and his “great compassion” are appealed to as the justification for seeking mercy and the obliteration (“blot out” or “wipe off”) of any transgression. The Hebrew word translated as “love” and “compassion” refers to the obligation God desirously and willingly entered into with his covenant with Israel.  (This type of covenant is seen in an appeal for deliverance from enemies in Psalm 31:15-16 and the request to remove divine judgment in Psalm 85:5-7). David does not deserve such mercy, neither can David demand forgiveness. But, according to the covenant the Lord made to help Israel in their weakness, David can willingly make confession of his sin and come back into agreement with God. In which case, God will remove David’s guilt and forgive his sin.

Three important verbs are used for the concept of “sin”:

1. 51:1, “transgression” is self-willed defiance of God and rebellion toward God’s will.
2. 51:2, “iniquity” is from a word that means bending and twisting. It refers to a state of distortion.
3. 51:2, “sin” is a common word used in this or some other description of sin over 500 times in the Old Testament. The base meaning is “to miss the mark.” The positive use of the word in reference to NOT “missing the mark” is found in Judges 20:16 in praise of the stone slingers defending the tribe of Benjamin:
             “Among all these soldiers there were seven hundred select troops who were  
               left-handed, each of whom could sling a stone at a hair and NOT miss.”

David uses three verbs to communicate what God’s “forgiveness” is like:

1. “to blot out” in 51:1 means “to obliterate.” This is an aggressive word that is translated “wipe off” in Proverbs 30:20 and Isaiah 25:8 and 2 Kings 21:13. It is used to refer to “obliterating” a name from a written document in Deuteronomy 9:14. This idea is captured in Isaiah 44:22:
                “I have swept away your offenses like a cloud,
                           your sins like the morning mist.
                 Return to me, for I have redeemed you.”
2. “wash away” in 51:2 is a word used for washing clothes in Exodus 19:10 and 2 Samuel 19:24. The Hebrew word comes from the verb which means “to pummel” and “to tread” which describe the process of beating clothes to wash them. This word is used in Jeremiah 2:22 when the Lord says that man is NOT able to “wash away” or “beat” his own sin out of his human nature or his memory:
                “Although you wash yourself with soap
                           and use an abundance of cleansing powder,
                 the stain of your guilt is still before me,”
                           declares the Sovereign Lord.”
3. “cleanse me” in 51:2b is also used of removing purifying silver in Malachi 3:3, of the wind removing clouds in Job 37:21, and of Naaman’s leprous skin being healed in 2 Kings 5:14.

"I therefore, yet not I, but the love of Jesus Christ, entreat you that you use Christian nourishment only and abstain from herbage of a different kind. I mean heresy. For those mix up Jesus Christ with their own poison, speaking things which are unworthy of credit, like those who administer a deadly drug in sweet wine."
- Ignatius to the Trallians
in 110 AD