Work out your own salvation with fear and trembling, for it is God who works in you, both to will and to work for his good pleasure. (Philippians 2:12–13)
God is the decisive worker here. Work out your own salvation . . . for it is God who works in you, the willing and the working. God wills and he works for his good pleasure. But believing this does not make Christians passive. It makes them hopeful and energetic and courageous.
Each day there is a work to be done in our special ministry. Paul commands us to work at doing it. But he tells us how to do it in the power that God supplies: believe him! Believe the promise that in this day God will be at work in you to will and work for his good pleasure.
It is God himself, graciously at work each moment, that brings the promise of future grace into our present experience. It is not the gratitude for past grace that Paul focuses on when explaining how we work out our salvation. I mention this simply because so many Christians, when asked what the motive is for obedience, will say gratitude. But that is not what Paul emphasizes when he talks about motive and power for our working. He focuses on faith in what God is yet to do, not just what he has done. Work out your salvation! Why? How? For there is fresh grace for every moment from God. He is at work in your willing and doing every time you will and do. Believe that for the challenges of the next hour and the next thousand years.
The power of future grace is the power of the living Christ — always there to work for us at every future moment that we enter. So when Paul describes the effect of the grace of God that was with him, he says, “I will not venture to speak of anything except what Christ has accomplished through me to bring the Gentiles to obedience — by word and deed” (Romans 15:18).
Therefore, since he would not dare to speak of anything but what Christ accomplished through his ministry, and yet he did, in fact, speak of what grace accomplished through his ministry (1 Corinthians 15:10), this must mean that the power of grace is the power of Christ.
Which means that the power we need for the next five minutes and the next five decades of ministry is the future grace of the omnipotent Christ, who will always be there for us — ready to will and ready to work for his good pleasure.