The other thing that is important to note is that all of these manuscripts were just a bunch of scrolls, rather than a single book, and these scrolls hadn’t necessarily been canonized yet. This means that there wasn’t a set list of books for the New Testament, because the New Testament is a canonical list of Scripture.  A process of canonization had been underway for Hebrew Scripture for several centuries at the time early Christians began writing. The roughly accepted timeline for this process is that the Pentateuch, or first five books of the Bible, was standardized around 500 BCE, the prophets in 300-200 BCE, and the remaining books achieving canonical status a few decades after the destruction of the Temple by the Roman in 70 CE.¹  This finalized list of official Scriptures made it easier to say “this is what it means to be Jewish” in the absence of the Temple of and the religious and political power structures that had previously helped to shape that identity.

Canonization of Christian scripture also helped to solidify the boundaries of what it meant to be Christian. The very earliest Christians were a diverse lot, ranging from forms of Jewish Christianity that still practiced circumcision and followed Mosaic law closely, to the somewhat Gnostic species of Christian recorded in the Gospel of John, to religious practices that we today wouldn’t recognizably Christian like serious Gnosticism and Manichaeism. Some of these differences are captured in the New Testament itself: Paul, for example, has quite a bit to say about circumcision, and reading between the lines in the Acts of the Apostles it seems likely that his mission to the Gentiles was not universally accepted by early Jewish Christians. Matthew, on the other hand, can plausibly be read as advocating for closely observing Mosaic law in some places.  

It is important to understand that this process of canonization occurred, and for that understanding to influence how we read Scripture.  For me, the things that I try to keep in mind are:

• Judaism as we understand it actually took shape after the earliest Christian writers wrote their Scripture, and so in some cases we should think about Scripture as arguing that Christianity, rather than the Judaism that descended from the practice of the Pharisees, should be the new, post-Temple form of Jewish religion.
• Orthodoxy did not exist when the various books that eventually formed the New Testament were written, and so there is some extent to which those books disagree with each other. These books each represent the specific viewpoint of a specific community or person, and these communities did not necessarily define Christianity identically. 
• The establishment of orthodoxy went hand-in-hand with the rise of the worldly power of Christianity. Once it became an established religion tolerated and supported by the emperors of Rome, the boundaries were more firmly drawn between orthodoxy and heresy.  It was only after this process had occurred that canonical lists of the books of the New Testament began to appear.  

Footnotes

[1]  It should be noted that among scholars there is some debate about the specifics of this timeline.  The book that I read about this was The Formation of Jewish Canon, which is a thorough but not necessarily accessible discussion of the topic.  <back to top>