Scripture has its authority from God, not from the church
Before I go any farther, it is worth-while to say something about the authority of Scripture, not only to prepare our hearts to reverence it, but to banish all doubt. When that which is set forth is acknowledged to be the Word of God, there is no one so deplorably insolent—unless devoid also both of common sense and of humanity itself—as to dare impugn the credibility of Him who speaks. Now daily oracles are not sent from heaven, for it pleased the Lord to hallow his truth to everlasting remembrance in the Scriptures alone [cf. John 5:39]. Hence the Scriptures obtain full authority among believers only when men regard them as having sprung from heaven, as if there the living words of God were heard. This matter is very well worth treating more fully and weighing more carefully. But my readers will pardon me if I regard more what the plan of the present work demands than what the greatness of this matter requires.
But a most pernicious error widely prevails that Scripture has only so much weight as is conceded to it by the consent of the church. As if the eternal and inviolable truth of God depended upon the decision of men! For they mock the Holy Spirit when they ask: Who can convince us that these writings came from God? Who can assure us that Scripture has come down whole and intact even to our very day? Who can persuade us to receive one book in reverence but to exclude another, unless the church prescribe a sure rule for all these matters? What reverence is due Scripture and what books ought to be reckoned within its canon depend, they say, upon the determination of the church. Thus these sacrilegious men, wishing to impose an unbridled tyranny under the cover of the church, do not care with what absurdities they ensnare themselves and others, provided they can force this one idea upon the simple-minded: that the church has authority in all things. Yet, if this is so, what will happen to miserable consciences seeking firm assurance of eternal life if all promises of it consist in and depend solely upon the judgment of men? Will they cease to vacillate and tremble when they receive such an answer? Again, to what mockeries of the impious is our faith subjected, into what suspicion has it fallen among all men, if we believe that it has a precarious authority dependent solely upon the good pleasure of men!