“What then? Are we to sin because we are not under law but under grace? By no means!” -Romans 6:15
At this point Paul is compelled to provide a refutatio for what he anticipates to be the next carnal argument against what he is teaching. In the previous verse (Romans 6:14), he had stated emphatically, “For sin will have no dominion over you.” And the reason is (since) “you are not under law but under grace.”
But since the carnal appetites of mankind tend to clamor against the mysteries of God, and Paul anticipates their cherry picking his last statement as justification for their licentious desires or as a means of proving him a heretic as he has already stated some have tried to do (Romans 3:7-8), he raises the rhetorical argument with his question: What then? Are we to sin because…?
And responds with another By no means!
But this is not some brush-off; it’s not a simple denial without an explanation or proof. It is the set up for an expanded explanation which will be treated in subsequent verses.
But what is important here is the fact that in Paul ready anticipation of the antinomian spirit of men, he indirectly heads off their heretical treatment of the law. The annulment of the Law’s curse is by no means an annulment of its precepts. Those that are under grace are not free from the spirit of the Law’s intent to teach men how to live righteously. Rather, they are empowered by grace to now do so effectively.