Even though the Jews had the advantages of the Mosaic Law and circumcision, their arrogance and fruitlessness offset these advantages. Divinely revealed religion is no substitute for trust and obedience toward God. Romans 2:17-29 are similar to Romans 1:18-32. In Romans 2:17-29, Paul showed that Jews are guilty before God just as he formerly proved all humanity guilty. In both sections he pointed out that man knew the truth but rejected it and consequently became guilty of idolatry, sensuality, and immorality. [source][source][source]
"In the previous section Paul addressed his Jewish readers in a relatively restrained manner. But here the mood changed. Once again he employed the diatribe style that he used in the opening verses of chap2. His tone became quite severe as he laid out before them the absolute necessity of bringing their conduct into line with their profession. From this point on to the end of the second major division ( Romans 3:20), we hear Paul the preacher convincing his listeners of their need for a different kind of righteousness. Although in another letter he claimed that his preaching was not eloquent ( 1 Corinthians 2:1-5), it is hard to deny that here in Romans we are dealing with the dynamic rhetoric of an evangelist bent on persuasion." [1][source]
"Paul here claims for the Jew nothing more than what the Jews of his day were claiming for themselves; every item on the list in Romans 2:17-20 is paralleled in Jewish literature of the time." [2][source]