Is the New Testament a Corpus in and of Itself?

When you're dealing with something that complex and varied, how do you go about deciding what is reliable for reconstructing history? And what is propaganda or metaphor or theology? How do you kind of unpick all of that? Well, that's it. It's really important because what one area of truth, of course, is historical truth. You know, what really happened in the past,. Some genres are not interested in that. But there are genres that are interested in what actually happened; so I think when you come to the gospels, for example, you get Matthew Markle, who can John the four gospels, they sound like biographies - right?