Why did God spare David's life when he committed adultery and murder?

We read in 2 Samuel 11 that David committed adultery with Bathsheba who was the wife Uriah, a man in David’s army. Bathsheba lets David know that she is pregnant as a result of the affair. David decides he will try to conceal his sin by putting Uriah in the most dangerous place in the battle so that he is killed. Once this happens, he marries Bathsheba who of course is already pregnant with his son. All appears good. God is angry and sends Nathan the prophet to rebuke David of his heinous sins. David up to this point behaved righteously with all the people of Israel – executing justice for the innocent and punishing the guilty. Sadly, David does the opposite because of his lust for Bathsheba. He punishes the innocent (Bathsheba and Uriah), and he justifies himself who at this point is guilty. David deserved death for what he did. 

So, why didn’t God end his life? 

Because of God’s mercy and grace. According to the law David should have been executed, but God chose to spare his life (Exodus 20). David was also immediately repentant once confronted with his sin (2 Sam 12:13).  Notice his exact words, “I have sinned against the Lord!” David laments his sin in detail in Psalm 51. Here is the thing that we MUST keep in mind. Although God spared David’s life, he suffered great consequences for his sins for the rest of his life. The son of the affair dies (2 Sam 12:18). His oldest son Amnon raped his sister Tamar (2 Sam 13:11-17). Absalom in defense of his sister Tamar had Absalom killed (2 Sam 13:28-29). Absalom attempted to usurp his father David’s kingdom (2 Sam 16:16). Absalom has sexual relations with David’s concubine on the roof the palace as an act of extreme contempt, humiliation and control of the kingdom (2 Sam 16:22). This evil act was Absalom claiming the throne for himself. The rebellion had gotten so bad that Ahithophel who was David’s counselor conspired to kill David. The counsel pleased Absalom.  

All this trouble befell David because of his sins of adultery and murder. When we repent, God forgives our sins, and cleanses us from all unrighteousness (1 John 1:9). But that does not mean we may not suffer retribution from the Lord for the sins we committed. Remember, all sin ultimately is sin against the Lord. We have offended The Almighty. For that disobedience we are chastened (Heb 12:5-11). God is our Father. He loves us, but just like our natural parents, they discipline us when we get out of line so our Heavenly does the same. This is what God did to David. In Psalm 119:71 it says, "It is good that I have been afflicted that I may learn your statues.”  The psalmist of 119 (possibly David) knew that in order to learn God’s ways, sometimes discipline has to be administered. 

Once again God is merciful and gracious. That is why David’s life was spared. David made this declaration in Psalm 32:1-2, “How blessed is he whose transgression is forgiven, whose sin is covered! How blessed is the man to whom the Lord does not impute iniquity, and whose spirit there is no deceit!”  

In Micah 7:18-19 we read,” Who is a God like you, who pardons iniquity and passes over the rebellious act of the remnant of His possession? He does not retain His anger forever, because He delights in unchanging love. He will again have compassion on us. He will tread our iniquities under foot. Yes, You will cast all their sins into the depths of the sea.”