There is a tendency for the body, the flesh, to arise from its condition of reckoned deadness; hence, the new nature needs to be continually on the alert to maintain its ascendency, to fight the good fight of faith and to gain the prize as an overcomer. These battlings of the new mind against the flesh are a good fight in the sense that they are fightings against sins and weaknesses that belong to the fallen nature. They are a fight of faith in the sense that the entire course of the Christian is a course of faith, as the Apostle says, "We walk by faith and not by sight." … It is a fight of faith in the sense that no one could keep up this battle against his own flesh and its propensities and desires, except as he can exercise faith in the promises and in the Lord as his Helper.
There is a distinction between keeping the body under and bringing it into subjection. We keep the body under when we suppress its efforts to control us, detach our earthly affections from its objects and prove impenetrable to its attacks. We bring it into subjection when the new heart, mind and will, laying hold of and enslaving it to God's will, makes it serve Truth, righteousness and holiness. Both of these things we must do to gain the prize of our calling. While other things must be done to gain eternal life, these are indispensable to overcoming. Whoever fails in this does not overcome. He will be a castaway as respects the prize.
1 Cor. 9:25, 26; 2 Cor. 6:4, 5; Rom. 8:13; Acts 1:25; 2 Pet. 2:15; Eph. 4:22; Col. 3:5; Jer. 6:30; Luke 9:25; 2 Cor. 13:5, 6.
