The old way of doing business was to (1) create an almost unassailable core of historical facts about Jesus, (2) add to those facts a handful of reasonably coherent episodes, and (3) bracket out all other claims about Jesus and leave those for the theologians. It is not uncommon to read biblical commentaries from the 1950s that simply note that a verse is "redactional" and say no more about it. (The reverse has become true in recent years, but that is a post for another time.)
In this method, the Fourth Gospel was bracketed out, redactional material was bracketed out, the infancy narratives were bracketed out, etc. One of the chief virtues of Dale Allison's program is the recognition that hagiography can be a vehicle for historical data. I say something similar about Matthew's redaction in this book. Allison cites this work a number of times, but not on this particular point.
Consider Luke's intro chapters. These chapters are almost universally regarded as hagiography by Jesus historians. But are we justified in bracketing these chapters out summarily as "ahistorical" as Gerd Luedemann does? I would argue that doing so is historiographical malpractice. I'll give two examples:
1. Luke chapter two writes that Jesus “grew and became strong, filled with wisdom, and the favor of God was upon him.” This verse is "redactional" and the old guard would set this obviously theological statement aside. After all, does the historian have any business including a statement about how God felt about Jesus? There are good reasons to label this verse "redactional". And, believe me, I'm not advocating a complete dismissal of redaction criticism. I think it is quite helpful to know what the editorial tendencies of the author are. But, and this is crucial, this verse tells us that Jesus was already approaching his teen years before his father departs from the narrative. Luke tells us here that Joseph was alive for most of Jesus' childhood. This corroborates what most historians hold to be true about Joseph. After all, if he fathered seven children, Jesus was probably no less than twelve before Joseph died. Just working with probabilities here, mind you: Mary probably didn't have seven children in less than ten years or multiple sets of twins or (sorry Jerome) remain a life-long virgin. So Luke's hagiography-looking story confirms something about Jesus' "hidden years": Joseph was probably around at least long enough to see his eldest son reach puberty.
2. Luke chapter two suggests that Jesus was circumcised. Again, one does not need to affirm the historicity of this particular episode to affirm that Luke confirms a historical fact derived from sociological comparison. Jesus, in all likelihood, was circumcised. Indeed, most historians would argue that he was even if Luke suggested otherwise. But it just so happens that Luke's theologically motivated "story" is of historical value in this case. Moreover, I can say so without having to prove this with multiple sources or a securely defended "core" of authentic material. This claim is singly attested and found in a very dubious segment of the narrative. No matter; Luke confirms that Jesus was indeed circumcised on the eighth day.
So bring on John, and Revelation, and the Infancy Gospel of Thomas. Why not? I'm not saying that we treat Revelation like Mark. What I'm saying is that we ought to be very wary about bracketing. It's all redational and none of it is historical in the Rankean sense... but nothing based in the real world ever is. We make judgments based on possibility, probability and plausibility. Look, I have no problem labeling something as fiction - I have the boot mark on my backside to prove it. But pretending that we're working with absolutes like "accurate" and "fictional" is [what is a synonym for "silly" that doesn't sound condescending?].
So what is the point in shading or coloring these verses with Black, Grey, Pink, and Red beads? Some of the black verses can give us some positively pinkish information. Or put another way (and I owe this quip to James Crossley): perhaps we're dealing with fifty shades of grey.