Theophylact of Ohrid

The answer follows again: no, there were preachers, many such were sent to them. From what is it evident that these who were sent were preachers? In response to this he cites the words of the prophet: "How beautiful are the feet of those who preach peace, who preach good things" (Isa. 52:7). The apostles, going throughout the world, proclaimed nothing other than the ineffable blessings and the peace of God with mankind. Therefore unbelief is the personal fault of those who did not accept the preachers.

Commentary on Romans ↗

Irenaeus

With regard to those (the Marcionites) who allege that Paul alone knew the truth, and that to him the mystery was manifested by revelation, let Paul himself convict them, when he says, that one and the same God wrought in Peter for the apostolate of the circumcision, and in himself for the Gentiles. Peter, therefore, was an apostle of that very God whose was also Paul; and Him whom Peter preached as God among those of the circumcision, and likewise the Son of God, did Paul [declare] also among the Gentiles. …

Against Heresies Book III ↗

Thomas Aquinas

Second, he moves from faith to hearing when he adds: or how shall they believe him of whom they have not heard? For one is said to believe things which are said to him by others and which he does not see: it is no longer because of your words that we believe, for we have heard for ourselves and we know that this is indeed the Savior of the world (John 4:42). …

Commentary on Romans ↗