John Chrysostom
But so that they might not think the Apostle accuses the Jews on his own authority, he set the prophet as their accuser.
Here it is Isaiah, who in a few words generally convicts them of their chief vice. Later it is David, who disclosed their faults in detail and with greater proof.
Paul says: I am not reproaching you for this. Hear what Isaiah said: "For the name of God is blasphemed among the nations because of you" (Isa 52:5).
Here are two more accusations. They not only insult God themselves, he says, but also lead others to do so.
What benefit, then, is there from teaching, if you do not teach yourselves? He has already said this above. Here he turns to the opposite point.
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You not only fail to teach yourselves and others what ought to be done. Worst of all, you not only fail to teach men to live according to the law.
You teach the opposite. You teach men to blaspheme God, which is contrary to the law.