"No man can walk in two directions at once. No man can go hopping along on one foot 'after the Spirit' toward life and at the same time hop along on the other foot 'after the flesh' toward destruction. He can walk but one direction. If he walks after the Spirit, however imperfectly, he is a Christian. His steps may be halting. He may stub his toe now and then, and occasionally he may even turn his ankle and limp rather badly. But still, as he walks after the Spirit, he walks but one direction. God is patient and understanding. He is not looking for perfection in men. But He is profoundly concerned about their direction. To those whose direction is toward Him through obedient faith in Jesus Christ, He imparts the perfection of His sinless Son and shares with them His own divine nature. But this He can only do for men whose direction is toward Him. And men can walk but one direction at a time. Whether a man walks 'after the Spirit,' or 'after the flesh,' he walks with both feet as the whole man."
Robert Shank, Life in the Son