This was a great aside starting Chapter 2:
The effort to repay God, in the ordinary way we pay creitors, would nullify grace and turn it into a business transaction. If we see acts of obedience as installment payments, we make grace into a mortgage... Let us not say that grace creates debts; let us say that grace pays debts.
Past grace is glorified by intense and joyful gratitude. Future grace is glorified by intense and joyful confidence. This faith is what empowers us for venturesome obedience in the cause of Christ.
I just love "venturesome obedience in the cause of Christ".