Since God hates sin and teaches his children to hate it also, it might seem logical to us that he would free us from the power of indwelling sin at the same time that he freed us from the power of sin to send us to hell. If he had done that, then we would have become completely perfect at the time of saalvation and been left to experience the rest of our lives here on earth in a sinless state. His will, however, has appointed otherwise.
Instead, at the moment of conversion he frees us from the spiritual power that our sin had to condemn us, but he leaves us with a sinful nature that will wage war against our new nature for the remainder of our lives. When he takes us to be with him in heaven, sin’s power over us will fully and finally be broken. In the meantime, it will often win. Many believers, naively underestimate the power of this inner sinful man that is left to do battle with our new nature.
– Duguid, Barbara; Extravagant Grace: God’s Glory Displayed in our Weakness; P&R Publishing; Philippsburg, NJ; copyright 2013; Page 59