Sin
This Psalm was written by David after he committed adultery. It is a Psalm of confession not only for his sin of adultery, but for all his sin. He says he had only sinned against God, but he had also sinned against the woman and the woman’s husband. This is his way of saying his sin against God is so great, his sin against others pales in comparison. He also says he was conceived in sin. This is teaching that he, and everyone else, was a sinner from the moment he was conceived. It’s not that he had done anything wrong at that point; it’s that his humanity also made him a sinner. He also calls out for God’s mercy, love and cleansing.
Take some time now to thank God for the cleansing you have received through Jesus. Ask him to clean your heart as well.