Thank you my dear friend for this very good question. The quick answer is that David, once he was confronted with his sin by Nathan the prophet, repented and asked God for forgiveness. Ahab never truly repented with his whole heart, and he continued in his sins, and thus he ultimately came under God’s judgment. 2 Samuel 12:1-23 gives the entire account of how God brought before David the great sin which he had committed by slaying Uriah and taking Uriah’s wife to himself. We see here the true conviction of sin and David’s confession: “So David said to Nathan, “I have sinned against the LORD…” (verse 13). Then in Psalms 51 we clearly see David’s heart-felt prayer of confession and repentance. The first 2 verses give us a sense of what true confession and repentance looks like: “Have mercy upon me, O God, according to thy lovingkindness: according unto the multitude of thy tender mercies blot out my transgressions. Wash me thoroughly from mine iniquity, and cleanse me from my sin.” Verses 9-12 are especially telling of the proper heart of one seeking the grace and mercy of God: “Hide thy face from my sins, and blot out all mine iniquities. Create in me a clean heart, O God; and renew a right spirit within me…Restore unto me the joy of thy salvation; and uphold me with thy free spirit.” Psalms 32:5 is another picture of true repentance: “I acknowledge my sin unto thee, and mine iniquity have I not hid. I said, I will confess my transgressions unto the LORD; and thou forgavest the iniquity of my sin…” David did not try to hide his sins from God once he was convicted of his sins, and he actively sought God’s mercy and grace by asking for forgiveness and cleansing.

However, King Ahab never demonstrated a truly contrite heart so far as I know in the Bible. Now, I do find one instance in 1 Kings 21 where King Ahab did put on sackcloth and humbled himself once he heard of the judgment which would come upon him and his house by the word of Elijah (see 1 Kings 21:1-29). But where was the change of heart? In verses 25-26 we read: “But there was no one like Ahab who sold himself to do wickedness in the sight of the LORD, because Jezebel his wife stirred him up. And he behaved very abominably in following idols, according to all that the Amorites had done, whom the LORD had cast out before the children of Israel.” Now 1 Kings 21:27 might lead us to believe that Ahab repented and meant to change his ways, and indeed, in verse 29 the Lord did note this man’s act of humbling himself so that the judgment was delayed until after his death, but we do not read of any true contrition of his spirit. In 1 Kings 22 we read that while there was not the calamity on Israel that Elijah had predicted during the 3 years after his supposed repentance, Ahab did nothing about dealing with his sinful wife Jezebel, and nor did he demonstrate any change of heart regarding the true God. Instead of repenting of his sins, he blamed the true prophets of God for telling him what he did not like to hear, that which God wanted him to understand and know: “…There is still one man, Micaiah the son of Imlah, by whom we may inquire of the LORD; but I hate him, because he does not prophesy good concerning me, but evil…” (1 Kings 22:8). Then we read that Ahab refused to listen to the true word of the Lord and so he became subject to the judgments predicted. 1 Kings 22 tells the rest of this sad story.

My dear friend, God is righteous in all His ways (Psalms 145:17), and He is Holy. He must judge sin. Still, He is also a God of grace and mercy, and He always has been. True repentance means that we change our minds and agree with God that we are sinners (Romans 3:23). There was no discernable change in Ahab, and so God’s judgment was righteous. But now in Ezekiel 33:11 we read about the grace and mercy of God, and His pleading for man to repent: “’As I live,’ says the Lord GOD, ‘I have no pleasure in the death of the wicked, but that the wicked turn from his way and live. Turn, turn from your evil ways! For why should you die, O house of Israel?’” In the New Testament, we see more of this long-suffering characteristic of God which causes Him to delay judgment upon sinners in hopes that they might repent: “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,” (2 Peter 3:9). David sought the mercy of God and His forgiveness, and He received it. Ahab had his chance as we all do, but Ahab only made a show of humility, and never truly repented. And how about any who may be reading this response, have you yet confessed and repented of your sins that you might be saved? In 1 John 1:9 we read: “If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.” (See also John 5:24; Romans 10:9; 1 John 4:10). Acts 17:30-31 tells us that it is time to repent and believe on the Lord Jesus Christ, because judgment is coming upon this earth for those who do not love God and who will not seek forgiveness for their sins. There can be forgiveness and eternal life through Jesus Christ for those who receive Christ Jesus as Savior and Lord (John 1:12 and 3:16; 1 John 5:11; Romans 10:9). I pray you believe on Christ today and live!  (SF)  (729.5)