The motivations that spring from full apprehension of God’s grace do not change the rules but do change the reasons for our obedience.  Grace encourages and enables us to serve God out of love for Him and desire for His glory.  Grace makes true obedience possible because a thankful response to unearned merit is motivated more by love for God than by love for self.

Brian Chapell, Christ-centered Preaching, p. 220