In giving verbal revelation about himself, to whom can God appeal for authentication? Reason, evidence, church councils? He uses these as confirming witnesses, but not as the grounds for the authority of his Word, nor as the basis of our acceptance of his Word.
"For when God made a promise to Abraham, since he had no one greater by whom to swear, he swore by himself, saying, 'Surely I will bless you and multiply you.' And thus Abraham, having patiently waited, obtained the promise. For people swear by something greater than themselves, and in all their disputes an oath is final for confirmation. So when God desired to show more convincingly to the heirs of the promise the unchangeable character of his purpose, he guaranteed it with an oath, so that by two unchangeable things, in which it is impossible for God to lie, we who have fled for refuge might have strong encouragement to hold fast to the hope set before us." (Hebrews 6:13-18 ESV)
There is some broad circular reasoning in this, which is acceptable when it comes to foundational principles. We can't make a case for reason without using reason. We can't authenticate empirical evidence apart from presuming the validity of such empirical evidence. In giving revelation God does not appeal to some higher standard, or an outside authority. He himself gives the standards for his own revelation. He does not have to make his revelation acceptable to all demands of human reason (though it is reasonable), nor with all standards for empirical evidence (though there is evidence). Nor is it his Word because a council or group declare it so (though many have). It is his Word because it is his Word, and he validates it. Or we might say, Scripture validates itself, no matter how many other witnesses and proofs we add to it, or arguments against it. John Calvin wrote, "God alone is a fit witness of himself in his Word… Scripture is indeed self-authenticated.” (Institutes 1.7.4-5)
Hence the books given by God will be spiritually discerned by the very people the books affect. At the core of the NT revelation is the gospel, which is "the power of God for salvation." (Romans 1:16) It is not the church that has given birth to the Scriptures, but the Scriptures have given birth to the church which will, in turn, recognize the voice of God. Jesus said, "My sheep hear my voice, ...and they follow me." (John 10:27)
Michael Kruger comments on this self-authenticating nature of God's special revelation, here in consideration of the NT canon:
"Central to the self-authenticating model of canon is the conviction that canonical books are recognized not only by their historical authenticity (apostolic origins) or their ecclesiastical acceptance (corporate reception), but fundamentally by the nature of their content (divine qualities). If these books are constituted by the work of the Holy Spirit, then Christians, who are filled with the Holy Spirit, should be able to recognize that fact." (Michael J. Kruger, Canon Revisited)