John Calvin Commentary Romans 2:27

"and shall not the uncircumcision which is by nature, if it fulfil the law, judge thee, who with the letter and circumcision art a transgressor of the law?" — Romans 2:27 (ASV)

By the letter and circumcision, etc. This expression means a literal circumcision. He does not mean that they violated the law because they had the literal circumcision; but because they continued, though they had the outward rite, to neglect the spiritual worship of God, that is, piety, justice, judgment, and truth, which are the chief matters of the law.