"I am what I am." These words had a different meaning for Paul and for God. For Paul, it was an expression of honesty: "I have been an S.O.B." For God, it was "Yes, but you are also an S.O.G., a son of God. And I'm going to give you the grace to believe it and the strength to live it." That doesn't mean that grace made him perfect or changed his personality. Paul was still there, flaws and all. But grace made him able to live with himself and less prone to project his problems on to somebody else. And when he accepted the fact that he was accepted as he was, he could become what God had always known him to be. And so he tells the Corinthians, "By the grace of God, I am what I am, and his grace toward me has not been in vain."
I Corinthians 15:1-11