One day Paul was killing Christians, the next day he was a Christian. One day Peter was a fisherman, the next day he was a fisher of men. Don’t judge someone based on that one day. If God can create a whole world in six days, He can truly create a new heart in one. — Unknown.
Moreover, I will give you a new heart and put a new spirit within you; and I will remove the heart of stone from your flesh and give you a heart of flesh. (Ezekiel 36:26)