Romans 2:17-29 ESV
But if you call yourself a Jew and rely on the law and boast in God and know his will and approve what is excellent, because you are instructed from the law; and if you are sure that you yourself are a guide to the blind, a light to those who are in darkness, an instructor of the foolish, a teacher of children, having in the law the embodiment of knowledge and truth— you then who teach others, do you not teach yourself? While you preach against stealing, do you steal? You who say that one must not commit adultery, do you commit adultery? You who abhor idols, do you rob temples? You who boast in the law dishonor God by breaking the law. For, as it is written, “The name of God is blasphemed among the Gentiles because of you.”
For circumcision indeed is of value if you obey the law, but if you break the law, your circumcision becomes uncircumcision. So, if a man who is uncircumcised keeps the precepts of the law, will not his uncircumcision be regarded as circumcision? Then he who is physically uncircumcised but keeps the law will condemn you who have the written code and circumcision but break the law. For no one is a Jew who is merely one outwardly, nor is circumcision outward and physical. But a Jew is one inwardly, and circumcision is a matter of the heart, by the Spirit, not by the letter. His praise is not from man but from God.