Some more thoughts on the matter, I am not sure that the typical Protestant (if one can speak of such a person) gives any thought to the question of "who decided what books would, and would not, be part of the Bible?". The Old Testament could be thought of as having come from the Jews, and that Christianity just took what was already in place (there would be some quibbling over the deuterocanonicals, or what they call the "apocrypha"), but as to the New Testament, there were all kinds of books floating around here and there, some "made the cut", some didn't. Who made that call, and on what authority?
Even if they were to say "well, the early Church decided that", the question then would be "and where does that same authority reside today, and if there is no such authority, when did it cease to exist?". I have found that many Protestant histories of the Church just more or less glide right over the particulars of how the early Church was organized and where authority resided.
This is probably an over-simplification, but Christians who look to the entire 2000-year history of the Church, without just sliding past the thousand-odd years from the time of Constantine to the various reformations, generally acknowledge that there was an unbroken succession of bishops, as well as a liturgy that consisted of both Scripture and the offering of the Eucharistic sacrifice. Catholics and Orthodox are of one voice on this, and Anglicans, though they take issue with Rome's judgment on their orders, affirm the same historicity that Catholics and Orthodox do.