Romans 2:25

περιτομή : the absence of the article suggests that the argument may be extended to everything of the same character as circumcision. ὠφελεῖ : Circumcision was the seal of the covenant, and as such an assurance given to the circumcised man that he belonged to the race which was the heir of God's promises. That was undeniably a great advantage, just as it is an advantage now to be born a Christian; but if the actual inheriting of the promises has any moral conditions attached to it (as Paul proceeds to show that it has), then the advantage of circumcision lapses unless these are fulfilled. Now the persons contemplated here have not fulfilled them. ἐὰν νόμον πράσσῃς : the habitual practice of the law is involved in this expression: as Vaughan says, it is almost like a compound word, “ if thou be a law doer ”. Similarly παραβάτης νόμου a law transgressor. The law, of course, is the Mosaic one, but it is regarded simply in its character as law, not as being definitely this law: hence the absence of the article. γέγονε : by the very fact becomes and remains.