John Calvin Commentary Romans 10:17

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

Faith then is by hearing, etc. We see by this conclusion what Paul had in view through the progression he formed; it was to show that wherever faith exists, God has already given evidence of His election there; and then, that He, by pouring His blessing on the ministry of the gospel—to illuminate people's minds by faith and thereby lead them to call on His name—had thus testified that the Gentiles were admitted by Him into a participation in the eternal inheritance.

And this is a remarkable passage regarding the efficacy of preaching; for he testifies that faith is produced by it. He had indeed previously declared that of itself it is of no avail; but that when it pleases the Lord to work, it becomes the instrument of His power. Indeed, the voice of man cannot penetrate the soul; and mortal man would be too highly exalted if he were said to have the power to regenerate us; the light of faith is also something more sublime than what can be conveyed by man: but all these things are no hindrances to God working effectually through the voice of man, so as to create faith in us through his ministry.

It must be further noticed that faith is grounded on nothing else but the truth of God; for Paul does not teach us that faith springs from any other kind of doctrine, but he expressly restricts it to the Word of God; and this restriction would have been improper if faith could rest on the decrees of men. Away then with all the devices of men when we speak of the certainty of faith. Hence also the Papal erroneous notion regarding implicit faith falls to the ground, because it tears faith away from the Word; and more detestable still is that blasphemy, that the truth of the Word remains suspended until the authority of the Church establishes it.