Was Paul a novice in the faith when he wrote the book of Romans? God would hardly allow a novice to write Scripture. The apostle Paul was one of the most mature Christians who ever walked the face of the earth. But he saw himself being torn—the flesh lusting against the spirit, and the spirit against the flesh. Paul was in the middle, having to make the choice. If he had not grown spiritually, he would never have seen the conflict; his mind would have passed right over it. Thus, on the one hand, Paul delighted in his understanding of the purpose and perfection of God's law, yet on the other, that insight produced much dismay in him because he could see how far short he fell, from time to time, of its perfection.
The existence of this inward conflict is not a sign that the person is not sanctified. As long as we are in the flesh, we will never be entirely free of this struggle. Human nature does not go down without a fight. It must be overcome! In a way, this evil entity within us actually becomes part of the means of our perfection.
Overcoming is a long process, and it requires diligent and humbling effort to subdue our human nature. However, we must never allow ourselves to fall into the attitude that all of our effort is somehow justifying us before God—even though it pleases God and gratifies us. The holiest of our actions, the holiest of the actions of the holiest saints, are still full of imperfections and defects. Even some of these are done from the wrong motive. They could even qualify as being nothing more than a splendid sin in God's sight. Nevertheless, we are saved by grace through faith. Even with that, God requires that we make an effort to do what we can on our part.