The Lord also has put away your sin; you shall not die. Nevertheless, because by this deed you have utterly scorned the Lord, the child who is born to you shall die. (2 Samuel 12:13–14)
This is outrageous. Uriah is dead. Bathsheba is raped. The baby will die. And Nathan says, “The Lord has put away your sin.”
Just like that? David committed adultery. He ordered murder. He lied. He “despised the word of the Lord.” He “scorned God.” And the Lord “put away [his] sin.”
What kind of a righteous judge is God? You don’t just pass over rape and murder and lying. Righteous judges don’t do that.
Here is what Paul said in Romans 3:25–26:
God put [Christ] forward as a propitiation by his blood, to be received by faith. This was to show God’s righteousness, because in his divine forbearance he had passed over former sins. It was to show his righteousness at the present time, so that he might be just and the justifier of the one who has faith in Jesus.
In other words, the outrage that we feel when God seems to simply pass over David’s sin would be good outrage if God were simply sweeping David’s sin under the rug. He is not.
God sees from the time of David down the centuries to the death of his Son, Jesus Christ, who would die in David’s place, so that David’s faith in God’s mercy and God’s future redeeming work unites David with Christ. And in God’s all-knowing mind, David’s sins are counted as Christ’s sins and Christ’s righteousness is counted as his righteousness, and God justly passes over David’s sin.
The death of the Son of God is outrageous enough, and the glory of God that it upholds is great enough, that God is vindicated in passing over David’s adultery and murder and lying.
And so God maintains his perfect righteousness and justice while at the same time showing mercy to those who have faith in Jesus, no matter how many or how monstrous their sins. This is good news.