What does 2 Samuel 12:23 mean?

While his son is dying, David prays and fasts. He knows God is gracious and merciful, and he hopes God might spare his son. After the infant dies, David washes, eats, and worships. He knows God is loving and sovereign. The greatest gift God gives him isn't the kingship, Jerusalem, or his son; it's His love and forgiveness (Psalm 51).

The servants are confused. David mourns while the child lives and worships after he dies. David explains that while the boy lived, David humbled himself in hope that God would change His mind. Now that the child is gone, he knows God has made His decision. It's time to move on.

Then David says a small thing with huge implications: "I shall go to him, but he will not return to me."

Among the great theological questions in Christianity is what happens to babies when they die. What happens to any child who dies before they're able to understand and repent from their sin? If we are all born sinners (Psalm 51:5), babies and young children aren't righteous enough to deserve to live in paradise for eternity. In Scripture, God acknowledges there are children who are too young to know "how to refuse evil and choose the good" (Isaiah 7:16). David tells us what will happen to them. In God's grace, He will bring them home. David hasn't lost his son forever. He will meet him again in paradise.