" The same active and passive role is found in Philippians 2:12 – 13: “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.” The encouragement to work out our own salvation is based on the promise that God will work in us—God will empower our work! For this very reason, those who believe in Jesus can confidently “strive … for the holiness without which no one will see the Lord” (Heb. 12:14). "
― Wayne Grudem , Christian Beliefs: Twenty Basics Every Christian Should Know