Romans 2:21

“Thou therefore which teachest another, teachest thou not thyself? etc..] Several charges are here brought against the Jews, even against their teachers; for though they are put by way of question, they are to be considered as so many assertions and matters of fact; thus, though they taught others, they did not teach themselves; they were blind leaders of the blind; they were ignorant of the law, of the spirituality of it; they were desirous to be teachers of the law, understanding neither what they said, nor whereof they affirmed: they were ignorant of the righteousness of God, of whom they boasted; and of the more excellent things of Moses, and the prophets, they pretended to explain; and…”

“Thou therefore ... - He who is a teacher of others may be expected to be learned himself. They ought to be found to be possessed of superior knowledge; and by this question the apostle impliedly reproves them for their ignorance. The form of a question is chosen because it conveys the truth with greater force. He puts the question as if it were undeniable that they were grossly ignorant; compare Matthew 23:3, “They say, and do not,” etc. That preachest - This word means to proclaim in any manner, whether in the synagogue, or in any place of public teaching. Dost thou steal? - It cannot be proved, perhaps, that the Jews were extensively guilty of this crime. It is introduced partly, no doubt,…”

“Thou dost not teach thyself - He does not teach himself who does not practise what he teaches. Dost thou steal, commit adultery, commit sacrilege - Sin grievously against thy neighbour, thyself, God. St. Paul had shown the gentiles, first their sins against God, then against themselves, then against their neighbours. He now inverts the order: for sins against God are the most glaring in an heathen, but not in a Jew. Thou that abhorrest idols - Which all the Jews did, from the time of the Babylonish captivity. Thou committest sacrilege - Doest what is worse, robbing Him "who is God over all" of the glory which is due to him. None of these charges were rashly advanced against the Jews of that…”

“2:21-22 Paul again uses the diatribe style to expose the inconsistency of Jewish claims (see study note on 2:1-5).”

“therefore: Psa 50:16-21; Mat 23:3-12; Luk 4:23, Luk 11:46, Luk 12:47, Luk 19:22; Co1 9:27; Gal 6:13; Tit 2:1-7 dost thou steal: Isa 56:11; Eze 22:12, Eze 22:13, Eze 22:27; Amo 8:4-6; Mic 3:11; Mat 21:13, Mat 23:14 Romans 2:22”