"And we also thank God constantly for this, that when you received the word of God which you heard from us, you accepted not as the word of men, but as it really is, the word of God, which is at work in you believers." (1 Thessalonians 2:13).
The Reformation made preaching of the Word of God the central event in the life and worship of the church. This is a healthy, biblical emphasis. Here is Calvin on why God has chosen to make the preaching of mere men the primary means of announcing the gospel of salvation,
"Therefore, to teach us that the treasure offered to us in earthen vessels is of inestimable value (2 Cor. 4:7), God himself appears and, as the author of this ordinance, requires his presence to be recognised in his own institution. Accordingly, after forbidding his people to give heed to familiar spirits, wizards, and other superstitions (Lev. 19:30, 31), he adds, that he will give what ought to be sufficient for all—namely, that he will never leave them without prophets. For, as he did not commit his ancient people to angels, but raised up teachers on the earth to perform a truly angelical office, so he is pleased to instruct us in the present day by human means. But as anciently he did not confine himself to the law merely, but added priests as interpreters, from whose lips the people might inquire after his true meaning, so in the present day he would not only have us to be attentive to reading, but has appointed masters to give us their assistance. In this there is a twofold advantage. For, on the one hand, he by an admirable test proves our obedience when we listen to his ministers just as we would to himself; while, on the other hand, he consults our weakness in being pleased to address us after the manner of men by means of interpreters, that he may thus allure us to himself, instead of driving us away by his thunder. How well this familiar mode of teaching is suited to us all the godly are aware, from the dread with which the divine majesty justly inspires them.
Those who think that the authority of the doctrine is impaired by the insignificance of the men who are called to teach, betray their ingratitude; for among the many noble endowments with which God has adorned the human race, one of the most remarkable is, that he deigns to consecrate the mouths and tongues of men to his service, making his own voice to be heard in them. Wherefore, let us not on our part decline obediently to embrace the doctrine of salvation, delivered by his command and mouth; because, although the power of God is not confined to external means, he has, however, confined us to his ordinary method of teaching, which method, when fanatics refuse to observe, they entangle themselves in many fatal snares." (Institutes IV:I:5).