Observe the grandeur of redeeming liberality in the apostle. In his heart of hearts he knows that salvation consists in nothing other than being one with Christ….
And yet he says, and says plainly, that a man thinking differently from all this, or at least quite unprepared to make this wholehearted profession of faith, is yet his brother in Christ. Even in such a one he believes that the knowledge of Christ, such as it is, will work, the new leaven casting out the old leaven until he too, in the revelation of the Father, shall come to the perfect stature of the fullness of Christ….
But how can he help him if he is not to press upon him his own larger and deeper and wiser insights?
The answer is clear. Paul will press, but not his opinion, not even the man’s own opinion. But he will press the man’s own faith upon him….
Obedience is the one condition of progress, and Paul entreats them to obey. If a man will but work that which is in him, will but make the power of God his own, then it will go well with him forevermore. Like his Master, Paul urges to action….
Whereto you have attained, walk by that.
George MacDonald, Your Life in Christ, p. 203-205