When Paul says that God fulfills our good resolves by his power through our faith, he means that we defeat sin and we do righteousness by being satisfied with all that God promises to be for us in Christ in the next five minutes, five months, five decades, and into eternity.
Here are three examples of how this might look in your life:
If you set your heart to give sacrificially and generously, the power of God to fulfill this resolve will come to you as you trust his future grace in the promise: “My God will supply every need of yours according to his riches in glory in Christ Jesus” (Philippians 4:19). And the promise: “Whoever sows bountifully will also reap bountifully” (2 Corinthians 9:6). And the promise: “God is able to make all grace abound to you, so that having all-sufficiency in all things at all times, you may abound in every good work” (2 Corinthians 9:8).
If you set your heart to renounce pornography, the power of God to fulfill this resolve will come to you as you trust his future grace in the promise: “Blessed are the pure in heart, for they shall see God” (Matthew 5:8). “It is better that you tear out your eye than that your whole body be thrown into hell” (Matthew 5:29). Much better. Wonderfully better. All-satisfyingly better.
And If you set your heart to speak out for Christ when the opportunity comes, the power of God to fulfill this resolve will come to you as you trust his future grace in the promise: “Do not be anxious how you are to speak or what you are to say, for what you are to say will be given to you in that hour” (Matthew 10:19).
May God increase our daily faith in his inexhaustible, blood-bought, Christ-exalting future grace.