It is only when God has transformed our nature and we have entered into the experience of sanctification that the fight begins. This warfare is not against sin; we can never fight against sin – Jesus Christ conquered that in His redemption of us. The conflict is waged over turning our natural life into a spiritual life. This is never done easily, nor does God intend that it be so. It is accomplished only through a series of moral choices. God does not make us holy in the sense that He makes our character holy. He makes us holy in the sense that He has made us innocent before Him. And then we have to turn that innocence into holy character through the moral choices we make. These choices are continually opposed and hostile to the things of our natural life which have become so deeply entrenched – the very things that raise themselves up as fortified barriers “against the knowledge of God.” We can either turn back, making ourselves of no value to the kingdom of God, or we can determinedly demolish these things, allowing Jesus to bring another son to glory.
(from My Utmost for His Highest)