SECOND QUESTION: THE NECESSITY OF SCRIPTURE
Was it necessary for the word of God to be committed to writing? We affirm.
1. As in the preceding question we have proved the necessity of the word, so in this we treat of the necessity of the Scriptures (or the written word) against the papists. For as they endeavor studiously to weaken the authority of Scripture in order the more easily to establish their unwritten (agraphous) traditions and the supreme tribunal of the pope himself; so, for the same reason, they are accustomed in many ways to impair its necessity in order to prove it useful indeed to to the church, but not necessary. Yea Cardinal Hosius does not hesitate blasphemously to say, “Better would it be for the interests of the church had no Scripture ever existed”; and Valentia, “It would be better had it not been written.”
2. As to the state of the question, keep in mind that the word “Scripture” is used in two senses: either materially, with regard to the doctrine delivered; or formally with regard to the writing and mode of delivery. In the former sense (as we said before), we hold it to be necessary with respect to God. For two thousand years before the time of Moses, he instructed his church by the spoken word alone; so he could (if he wished) have taught in the same manner afterwards, but only hypothetically (on account of the divine will) since God has seen fit for weighty reasons to commit his word to writing. Hence the divine ordination being established, it is made necessary to the church, so that it pertains not only to the well-being (bene esse) of the church, but also to its very existence (esse). Without it the church could not now stand. So God indeed was not bound to the Scriptures, but he has bound us to them.”
3. Therefore the question is not whether the writing of the word was absolutely and simply necessary, but relatively and hypothetically; not for every age, but now in this state of things; nor relatively to the power and liberty of God, but to his wisdom and economy as dealing with man.
Institutes of Elenctic Theology – Volume 1 (Phillipsburg, NJ; P&R Publishing; 1992) p. 57.