Well, historical facts indicate to the contrary. Codex Sinaiticus, then oldext complete Christian Bible (c. 340 AD) contains the Epistle of Barbanus and Sherpherd of Hermes as well as other books of the Old and the New Testament. Clearly some of the fathers thought different.
Protestants would argue that we rest our affirmation on those books that were deemed inspired by the VERY EARLY Church fathers (the Hebrew fathers) rather than those who came along 300+ years later
Which Hebrew fathers? Some of the NT deuterocanonicals (i.e. 1 and 2 Peter, and others, were not written until the 2nd century when all those "Hebrew fathers" were dead!).
I remember two weeks after my conversion, my Sunday School teacher telling me the virgin birth couldn't possibly happen. If you're going to doubt the inspiration of God's word, this is the place to start for this is indeed one of the greatest miracle of all. Are you prepared to say that the virgin birth is a made up story or question the inspired story as told by God? You might as well chuck the whole thing out the window and become a Baal worshipper or something.
I can understand an agnostic or atheist not believing in God's inspired writings, but I sincerely don't understand how a professing Christian cannot understand the inspiration of God's word.