In previous posts I discussed how we got the canon of the Hebrew Bible/Old Testament. I now will discuss the formation of the New Testament canon. Why these 27 books? Who decided? When? On what grounds?
This will be the focus of my next book, which I am beginning to read and think seriously about. The following is the basic overview that I provide in my book The Bible: A Historical and Literary Introduction 2nd ed (Oxford University Press).
This will take two posts.
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We are much better informed about the formation of the canon of the New Testament (than for the OT), in no small part because we have the writings of later church fathers who explicitly discuss the matter. We do not have nearly as much information as we would like—as is true for almost every set of historical events from the ancient world—but we have enough to give us a good idea of what motivated Christians to come up with a list of canonical books, what criteria they followed in deciding which books should be included, and

Billy Carson said on a podcast that the ethiopian bible is the “most complete bible” with the implication being that it is most accurate and authentic bible. In reality, is there any such thing as “the most complete bible”?
No. I’m not sure what he might have meant.
I’m not ready to accept your claim that Jesus doesnt identify himself with the Son of Man, but I sincerely want to understand the truth. With that, I’d like to hear your thoughts on Mark 9:9–13. Jesus teaches that the Son of Man will rise from the dead (implying himself?) The disciples ask about the expectation that Elijah comes first, presumably referencing Malachi 4:5. Jesus affirms this expectation, saying Elijah does indeed come first/restores all things. Yet he immediately adds that the Son of Man must suffer and be treated with contempt, and then says that Elijah has already come and was treated however people wished.
Is Jesus intentionally linking the suffering/contempt of the Son of Man with the treatment Elijah received? If so, is he suggesting Elijah is the Son of Man? Since Jesus speaks of Elijah in the past tense “he has come, and they did to him…” is he identifying Elijah with John the Baptist? Does he mean this literally, as though John was Elijah returned in the flesh? Finally, how does all of this relate to Jesus’s understanding of the Son of Man- did he see John as the Son of Man in any sense?
One of the most important issues in the study of the historical Jesus (since the 18th century) involves differentiating between what Jesus is recorded as saying in the Gospels with what hte historical Jesus himself said. In the Gospels he definitely identifies himself as the Son of Man. Did he actually do so? I very much do not think so. I explain why in a number of places, but maybe the best one to look at is my book Jesus: Apocalyptic Prophet of the New Millennium, where I explain why the Gospels pose problems for knowing what Jesus actually said and how historians have worked to get around these problems.
You write that, “the pseudonymous author of 2 Peter spoke of the letters of Paul and also included them among the Scriptures”; but when you write about “1 Timothy, which quotes two sayings as ‘Scripture'”, you don’t mention that 1 Timothy is also largely seen as pseudonymous.
Would it be true to say that only pseudonymous New Testament writers make the claim that other NT texts are “scripture”?
Yes, just those two.