A cliche of critical Bible scholarshio is to treat history and theology as antithetical categories. For instance, they may regard John as the least historical of the Gospels because it contains the most theological interpretation.
Conservative scholars have, of course, made the banal observation that critical scholars are guilty of erecting a false dichotomy. But I'd like to put a sharper point on that observation.
It's true that the Gospels are more than a record of events. They are interpreted events. But not only is that consistent with their historicity, but that's to be expected if they are based on eyewitness testimony.
Most everyone is a historian. I'm a historian with respect to my own time and place. What I myself have seen. People I personally knew.
When historians and biographers write about public figures or events in the recent past, they try to interview close acquaintances. That's because a close acquaintance can be an invaluable source of information. Parents know a lot about their kids, and vice versa. Siblings know a lot about each other. Childhood friends know a lot about each other. And this involves two types of information:
i) What the subject thought, said, did.
A close acquaintance may have a detailed knowledge of part, most, or even all of the subject's life. In many cases he has firsthand knowledge of what the subject said and did. He was there when it happened. He saw it or heard it.
Likewise, that subject may have told him about things he did in the past. So the close acquaintance is getting that straight from the horse's mouth.
ii) Why the subject thought, said, did what he did.
In addition to knowing what he thought, said, and did, a close acquaintance may know why that's the case. And these typically go together. There are several factors that may motivate people to think, say, and believe in certain ways:
a) If you know a person well enough to know their character traits. Their temperament. Their values. Their likes and dislikes. If you've been around them often enough and long enough to observe a pattern. That makes them predictable. You usually know what to expect. We are creatures of habit. We have formative influences. We rarely act out of character.
b) They may tell a close acquaintance why they did something, why they like or dislike sometime. They will explain their actions.
c) If you know the events leading up to a particular decision in his life. Circumstances constrain our field of action. We choose from the available options.
One thing leads to another. What we think, said, or did is in response to prior events. It has a context in a larger chain of events.
As a result, a close acquaintance is in privileged position to interpret the subject's action. Give a reason for why the subject thought what he thought, said what he said, and did what he did. This isn't the fictional omniscient narrator; rather, this is realistic.
This is why a good historian or biographer will seek out people who knew the subject well, and question them, not only on the facts, but on the motivations. A close acquaintance has that interpretive frame of reference.