After you have been saved and try to follow hard after Christ there comes a point of realization. When you try to be and live holy , you find an enemy within you. You already dealt with your past and have received a new heart and have victory over sinful actions but you realize that there is some corruption deeper within that wars against what you long to be. God will show you indwelling sin in the heart. The good news is that there is also deliverance for that!