Romans 8:12 : So, then, brethren, we are debtors, not to the flesh, to live after the flesh. "So then" seems to cover the whole argument beginning at Romans 5:12. "We are debtors" to what? Not to the flesh we have already learned that attending to the flesh leads to death. We could not be under obligation to follow a course that leads to our own destruction. To live after the flesh is to live a worldly life. If we are not debtors –to the flesh, then what? Evidently to our spirits that is, we are obligated to attend to the things of the spirit. As the spirit controls the body, we must keep our spirits pure. Also, the spirit endures to eternity. We must guard it well, lest we fail of eternal life.