For we hold that a man is justified by faith apart from works of law. Or is God the God of Jews only? Is he not the God of Gentiles also? Yes, of Gentiles also, since God is one; and he will justify the circumcised on the ground of their faith and the uncircumcised through their faith.Romans 3:28-30
It’s evident that when Paul says, “We hold that a man is justified by faith apart from works of the law,” he’s referring to the Law of Moses, not the moral law. This is clear from the next sentence: “Or is God the God of Jews only?”
His argument is this:
If a man is justified by works of the law, then God is the God of Jews only, since only Jews have the law.
But God is God not only of the Jews, but of the Gentiles also.
Therefore a man is not justified by works of the law.
If “the law” referred to the moral law, then the premise underlying Paul’s argument, that “only the Jews have the law,” would be false.