In Psalm 51:12, David continues his prayer for forgiveness; he wants to do what is right. He recognizes the joy of God's salvation and wants to be restored to it.
"Then I will teach transgressors Your ways, and sinners shall be converted to You" (51:13). It is often the case that those who are most evangelistic are those who have really "tasted" God's forgiveness, so to speak. David now knows how serious his sin was; therefore he also understands how great God's forgiveness is (cf. Luke 7:47; 22:32). We must endeavor to understand the depth of our wickedness before we will fully appreciate the gift of redemption.
David cannot properly speak to others until his personal problem with sin is resolved. But, after he is delivered, he will have no restraint in proclaiming God's goodness - "my tongue shall sing aloud of Your righteousness" (Psa. 51:14). How can those of us who have been cleansed by the blood of Christ behave any differently? Let us praise our merciful God and tell the world of His righteousness!
In verse 15, David reiterates that his lips will be open if God forgives him.
David expressed to God in Psalm 51:16 - "For You do not desire sacrifice, or else I would give it; You do not delight in burnt offering." An animal sacrifice could not intrinsically take care of David's sin problem, and he knew it. More has always been required.
"The sacrifices of God are a broken spirit, a broken and a contrite heart - these, O God, You will not despise" (51:17). This is truly what God has always wanted from man. He wants us to come to Him without arrogance or self-justification or ignoring our sins. He wants us to throw ourselves upon His mercy and submit to His will.
In verse 18, David's concern is not only for himself but for his people. He asks God to strengthen Jerusalem.
As the psalm closes, we see that David was not ignorant of the physical laws of sacrifice for the Hebrew people. However, he understands that sacrifice is vain if the heart is not in it. But, when one has the proper attitude and then does what God has asked, God will accept his worship (cf. John 4:24; Micah 6:6-8). David does not reject animal sacrifices in God's process of pardon, but he recognizes their proper place with a broken spirit and contrite heart. What a powerful psalm!
Grace is when God gives us what we do not deserve (regarding blessings). Mercy is God's refusal to give us what we do deserve (regarding punishment). Mercy is a wonderful attribute of God. David begged God for it, and God was merciful to him (cf. II Sam. 12:13). Of course, that doesn't mean he escaped all temporal consequences. David suffered many long-term consequences and a great deal of suffering for his sins against Uriah. There is a lesson for us there, too.
Praise be to God that He is still merciful! While on this Earth, we will always need God's mercy (cf. Rom. 3:23; I John 1:8,9). Friends, aren't you glad that...
"The Lord is not slack concerning His promise, as some count slackness, but is longsuffering toward us, not willing that any should perish but that all should come to repentance" (II Pet. 3:9). The wise will listen, learn, and live accordingly!