Richard Carrier on the Formation of the NT Canon (2000)

Contrary to common belief, there was never a one-time, truly universal decision as to which books should be included in the Bible. It took over a century of the proliferation of numerous writings before anyone even bothered to start picking and choosing, and then it was largely a cumulative, individual and happenstance event, guided by chance and prejudice more than objective and scholarly research, until priests and academics began pronouncing what was authoritative and holy, and even they were not unanimous. Every church had its favored books, and since there was nothing like a clearly-defined orthodoxy until the 4th century, there were in fact many simultaneous literary traditions. The illusion that it was otherwise is created by the fact that the church that came out on top simply preserved texts in its favor and destroyed or let vanish opposing documents. Hence what we call "orthodoxy" is simply "the church that won." Link.