John Calvin Commentary Romans 2:23

"thou who gloriest in the law, through thy transgression of the law dishonorest thou God?" — Romans 2:23 (ASV)

Thou who gloriest in the law, and so forth. Though every transgressor dishonors God (for we are all born for this purpose—to serve him in righteousness and holiness), yet he justly attributes a special fault in this respect to the Jews.

For, as they professed God as their Lawgiver and yet took no care to shape their lives according to his rule, they clearly proved that the majesty of their God was held in so little regard by them that they easily despised him.

In the same way, those today who talk idly about its doctrine, while still trampling it underfoot by their unbridled and licentious way of living, dishonor Christ by transgressing the gospel.