Romans 2:25-28

Circumcision [the sign of the covenant of Abraham] is indeed of value if you practice the Law; but if you habitually break the Law, your circumcision has become uncircumcision [it is meaningless in God’s sight]. So if the uncircumcised man keeps the requirements of the Law, will not his uncircumcision be regarded [by God] as circumcision? Then he who is physically uncircumcised but keeps [the spirit of] the Law will judge you who, even though you have the written code and circumcision, break the Law. For he is not a [real] Jew who is only one outwardly, nor is [true] circumcision something external and physical.