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. He 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 of future grace: 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 arriving each moment, that brings the future into the present. It is not the gratitude for past grace that Paul focuses on when explaining how he “worked harder than any of them.” It is fresh grace for every new conquest in his missionary labor.
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 tomorrow’s 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.