I've come to see that sin is not something that is just turned off. In Genesis 3:22, after Adam & Eve sinned, God exiles them from the garden of Eden so they wouldn't eat of the tree of life & live forever. This means that no matter how long we live, even as Christians and even with the Holy Spirit in us, we will never progress to a point in which we no longer sin. Solomon discovers this fact when thinking of wisdom in Ecclesiastes 7:15-16, saying that both the fool and the wise will die.