Understanding God doesn’t come naturally to us. I think of the old testament as god creating solid concrete learning tools so humans can understand cosmic intangible truths.
So he has a holy of holies which is the location of God. Sacrifices of animals to show that sin is important. But now more of god’s plan is out there, the temple and the sacrifice are revealed as much less specific, more universal truths.
Here we have a story about how violence between each other is also a cosmic injustice against God. The universe knows what we did last summer. So he sends a real man to be the voice of the universal God.
Nathan the prophet knows and declares David’s sin. And the sin has practical consequences: the baby he fathered with the murdered mans wife does not live.
Another consequence is that “the sword will not depart from him” which I take to mean David will have to be a fighter for the rest of his life. After all this incident started when he delegated a battle and stayed home… To lust.
God must have mixed feelings about rest… It’s sometimes when we take him most for granted, get up to the most mischief.
I think sin works this way in this story for the purpose of the story. I don’t think the message is that we’ll always have a prophet to tell it out to us, or that the babies of cheating will always die.
It’s to teach us that sin matters. injustice matters. I wince when God says his punishment for the sin will be out in the sun, when David acted in secret.
Could you stand it if everyone could see your worst thoughts and actions? Well you shouldn’t be able to forget that god can. Ethics matter, sin matters.