Philippians 2:12-13 Fear and Trembling

Philippians 2:12-13 presents two seemingly contradictory ideas: "If it is to be, it is up to me" vs "Let go and let God." This tension has been the source of epic debate throughout Christian History via Augustine v Pelagius, Luther v Erasmus, and Calvin v Arminius. Rather than contention, this passage presents us with astouning wonder ("fear and trembling") as we appreciate that God Himself produces the desire and provides the power for us to go and do His work. 

Therefore, my dear friends, as you have always obeyed—not only in my presence, but now much more in my absence—continue to work out your salvation with fear and trembling, for it is God who works in you to will and to act in order to fulfill his good purpose.
— Philippians 2:12-13