Albert Barnes Commentary Romans 10:17

"So belief [cometh] of hearing, and hearing by the word of Christ." — Romans 10:17 (ASV)

So then faith comes, etc. I take this to be clearly the language of the objector. As if he had said: By the very quotation you have made from Isaiah, it appears that a report was necessary. He (Isaiah) did not condemn men for not believing what they had not heard; rather, he complains of those who did not believe a message actually delivered to them. Even by this passage, therefore, it seems that a message was necessary—that faith comes by hearing, and hearing by the Divine message. It could not be right, therefore, to condemn those who had not obeyed the gospel because they had not heard it, and hence not right to make salvation dependent on a condition which was, by God's arrangement, put beyond their power. The very quotation from Isaiah, therefore, confirms the objection in Romans 10:14-15.

By hearing. Our translation has varied the expression here, which is the same in two places in the Greek: "Isaiah said, Who has believed our report? (th akoh). So then, you must admit that faith comes by that report (ex akohv), and therefore this report or message is necessary." When it is said that faith comes by hearing, it is not meant that all who hear actually believe, for that is not true; but that faith does not exist unless there is a message, or report, to be heard or believed. It cannot come otherwise than by such a message; in other words, unless there is something made known to be believed. And this plainly shows us the importance of the message, and the fact that men are converted by the instrumentality of truth, and of truth only.

And hearing. And the report, or the message (h akoh), is by the word of God; that is, the message is sent by the command of God. It is his word, sent by his direction, and therefore, if withheld by him, those who did not believe could not be blamed. The argument of the objector is that God could not justly condemn men for not believing the gospel.