The reading is from St. Paul's Letter to the Romans 2:14-28

Brethren, when Gentiles who have not the law do by nature what the law requires, they are a law to themselves, even though they do not have the law. They show that what the law requires is written on their hearts, while their conscience also bears witness and their conflicting thoughts accuse or perhaps excuse them on that day when, according to my gospel, God judges the secrets of men by Christ Jesus. But if you call yourself a Jew and rely upon the law and boast of your relation to God and know his will and approve what is excellent, because you are instructed in the law, and if you are sure that you are a guide to the blind, a light to those who are in darkness, a corrector of the foolish, a teacher of children, having in the law the embodiment of knowledge and truth - you then who teach others, will 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, do you dishonor God by breaking the law? For, as it is written, "The name of God is blasphemed among the Gentiles because of you." 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 those who are physically uncircumcised but keep the law will condemn you who have the written code and circumcision but break the law. For he is not a real Jew who is one outwardly, nor is true circumcision something external and physical.