“Who knows whether the LORD will be gracious to me, that the child may live?”
Tchividjian, Tullian (2010-04-23). Surprised by Grace: God's Relentless Pursuit of Rebels (p. 99). Crossway. Kindle Edition.
Why do Calvinist's pray? So many mistakenly believe that Calvinism is fatalistic, that if God has already decided you fate, why try to do anything about it? Why not just live as you please, because God has already
Consider David here for a moment. God has already told him the child will die. David has no reason to doubt this. But he hopes. He hopes that God might be gracious in this one thing. Yet he accepts. He accepts that God may not.
So we pray. We work out our salvation "with fear and trembling." I believe one of the reasons we do this is because of all the people who can fool us, we are the one we need to be most wary of. We worship and trust. We don't take God for granted.
So what does David do when the child dies? He worships God. And those around him think he is crazy for doing it. But David knew what he was doing. After all, he was a man after God's own heart.