John Chrysostom

"Well," he praises what they said, then he alarms them again by saying, "Because of unbelief they were broken off, and thou art grafted in by faith." So here another encomium, and for the other party an accusation. But he again lays their pride low by proceeding to say, "be not high-minded, but fear." For the thing is not matter of nature, but of belief and unbelief. And he seems to be again bridling the Gentile, but he is teaching the Jew that it is not right to cling to a natural kinsmanship. …

Homily on Romans 19 ↗

Cyprian

But I hear that some infect your number, and destroy the praise of a distinguished name by their corrupt conversation; whom you yourselves, even as being lovers and guardians of your own praise, should rebuke and check and correct. For what a disgrace is suffered by your name, when one spends his days in intoxication and debauchery, another returns to that country whence he was banished, to perish when arrested, not now as being a Christian, but as being a criminal! …

Epistle VI ↗

Thomas Aquinas

Then when he says, well, he excludes the objection. First, he assigns the reason why the Jews fell away and the gentiles were promoted, saying: well, i.e., it is good that God permitted branches to be broken off, so that you might be grafted in, but consider the cause of the breaking off of the branches. It is because of unbelief, i.e., because they refused to believe in Christ, they were broken off: for you are among unbelievers and destroyers (Ezek 2:6); if I speak the truth, why do you not believe me? (John 8:46). …

Commentary on Romans ↗