It takes a long time for sinful instincts to become pure, for tendencies toward what is evil to be transformed into tendencies toward what is good, lovely, and pleasing to God. The man who quits drugs will still react when he catches a whiff and the woman who gave up alcoholism will still struggle when she takes a sip. You can be a Christian for many years and still find your heart instinctually swayed toward what you once loved and what once drew your heart.