15 What then? shall we sin, because we are not under the law, but under grace? God forbid. (Romans 6:15 KJV)
William Burkitt’s Commentary
Here Apostle Paul starts an objection, which some licentious person might be ready to make: “If we are not under the law which condemns sin, but under the covenant of grace which allows the pardon and promises the forgiveness of sin why may we not then go on in sin and continue in sin, forbidden by the law, seeing we are not under the law?” The apostle rejects such a suggestion with his usual note of detestation, God forbid.
From hence we may learn, That it is a high abuse of the covenant of grace to suppose or imagine that it countenances any licentiousness or allows any liberty to sin. The design of the new covenant is to recover from sin not to encourage any to continue in sin.
Learn, 2. That such doctrines and inferences are to be abhorred, which from the grace of God, in mitigating the law, would infer an utter abrogation of the law, denying that it has a directive regulation power over a believer. True, we are delivered from the curse and condemnatory sentence of the law, from the severity and rigorous exactions of the law: But to refuse obedience to the law under the pretence of Christain liberty, to sin because we are not under the law but under grace is turning the grace of God into wantonness and to use our Christian liberty as an occasion to the flesh.