If there had been no prophet like Nathan””no piercing, prophetic word””David could have ended up like Saul: spiritually dead, with no Holy Ghost guidance, having lost all intimacy with God.
As David listened to Nathan’s loving but searing word, he remembered the time a previous king had been warned by a prophet. David had heard all about the prophet Samuel’s warning to King Saul. And he had heard about Saul’s halfhearted response, confessing, "I have sinned.” (I don’t believe Saul cried from his soul, as David did, "I have sinned against the Lord!”)
David saw firsthand the ruinous changes that befell Saul. The once godly, Spirit-led king continually rejected the Spirit’s reproving words, delivered by a holy prophet. Soon Saul began to walk in self-will, bitterness and rebellion. Finally, the Holy Ghost departed from him: "Because thou hast rejected the word of the Lord, he hath also rejected thee from being king” (1 Samuel 15:23). "The Lord . . . departed from Saul” (18:12) and Saul ended up turning to a witch for guidance. He confessed to her, "God is departed from me, and answereth me no more, neither by prophets, nor by dreams: therefore I have called thee, that thou mayest make known unto me what I shall do” (1 Samuel 28:15).
David remembered all the madness, ugliness and terror surrounding this man who had shut out God’s word. Suddenly, the truth pierced his own heart: "God is no respecter of persons. I have sinned, as Saul did. And now here’s another prophet, in another time, giving me a word from God, as Samuel gave to Saul. Oh, Lord, I’ve sinned against you! Please don’t take your Holy Spirit from me, as you did from Saul.”
David wrote, "I acknowledge my transgressions: and my sin is ever before me. Against thee, thee only, have I sinned, and done this evil in thy sight. . . . Purge me. . . . Create in me a clean heart. . . . Cast me not away from thy presence; and take not thy Holy Spirit from me” (Psalm 51:3-4, 7, 10-11).