Circumcision has value if you keep the law; but if you break the law, your circumcision has turned into uncircumcision.
In context
23You boast in the law—do you dishonor God by breaking it? 24For, as it stands written, “God’s name is blasphemed among the Gentiles because of you.” 25Circumcision has value if you keep the law; but if you break the law, your circumcision has turned into uncircumcision. 26So if an uncircumcised man keeps the just requirements of the law, will his uncircumcision not be counted as circumcision? 27The one who is physically uncircumcised and yet fulfills the law will judge you, who have the letter and the circumcision and still break the law.