Scholars are notorious for disagreeing with each other, as well as with having bizarre ideas. I personally believe that not all scholars are created equal. In particular, some are more objective than others. In the area of religion, some people become experts only to defend the positions with which they started. Others try to nail out the details of a position that was wrong to begin with, and they predictably end up in a wacky place.
I personally take a lot of stock in consensus. When those who are truly experts on a subject pretty much agree on something, I take that very seriously. There is an important caution here. For example, the book of Hebrews was the focus of my doctoral work and I have published two books and several articles on it. I think it is fair to consider me an expert on Hebrews.
But I am not an expert on the Gospel of John. A position I have on John doesn't count as much intrinsically as if a Johannine scholar were to speak. Frankly, even on the subject of Hebrews, I am more of an expert on some aspects than others. So when I speak of consensus on something like the Gospel of Matthew, I mean experts on Matthew more than I would mean a New Testament scholar in general.
So I have a PhD in New Testament. I have written a New Testament survey textbook. So I have explored a little the question of how the gospels were created. Am I an expert on that subject? Maybe we should say I am more of an expert than your pastor probably is, but less of one than those for whom this subject is their specialty.
Nevertheless, I want to tell you a story. I think it is a story that most of those who truly are experts would agree with. I want to tell you the story of how someone started with the Gospel of Mark and ended up with the Gospel of Matthew...