Περιτομὴ μὲν γὰρ ὠφελεῖ ἐὰν νόμον πράσσῃς

Says 2:25 says περιτομὴ μὲν γὰρ ὠφελεῖ ἐὰν νόμον πράσσῃς· ἐὰν δὲ παραβάτης νόμου ᾖς, ἡ περιτομή σου ἀκροβυστία γέγονεν (BSB "Circumcision has value if you observe the law, but if you break the law, your circumcision has become uncircumcision"). The μέν … δέ pair balances the two conditions. Both are ἐάν with the present subjunctive, general conditions that make no assumption about which is true.

Says ὠφελεῖ is used absolutely, "is of benefit" (Abbott-Smith lists Rom 2:25 under the absolute use: "to help, benefit, do good, profit"). The question returns at 3:1, τίς ἡ ὠφέλεια τῆς περιτομῆς; (BSB "what is the value of circumcision?"). νόμον πράσσειν, "to practice the law," is set against παραβάτης νόμου, "a transgressor of the law" (also 2:23, 27).

Says γέγονεν is perfect: "has become," a result that stands. Circumcision counts as uncircumcision.

Implies Paul does not deny the value of circumcision; he ties its value to keeping the covenant it signified. 3:1–2 shows the benefit is real ("Much in every way"). 2:25 denies only that the sign protects the transgressor at the judgment (2:12–13).