Threatenings and Promises
Most antinomians were of the view that Christians obey the law out of gratitude for all that the triune God has done for them. But Reformed theologians, while agreeing that gratitude is a motive for obedience, insisted on the necessity of law keeping because of the Creator-creature distinction (WCF 19.5). Not only can man not escape the obligation to keep God’s law, but man’s decision to keep God’s law because it is God’s law is in fact a sign of grace, not a sign of being unconverted or having a legalistic spirit, as the antinomians argued. Attached to God’s law are threatenings and promises, which are legitimate reasons why a Christian should keep the moral law.
Mark Jones, Antinomianism: Reformed Theology's Unwelcome Guest? (Phillipsburgs, New Jersey: P&R Publishing, 2013), 36