AP: The only sure thing we can do is critically analyze those Gospels that were written not too long after Jesus' life. We look at them critically-speaking in order to weed out fantasy from reality. We put a big magnifying glass over the texts in order to find out what's history and what is pure theology.
The most ancient writings are the four Gospels that have been accepted as canonical Gospels by the early Church. Mark was written first. Matthew and Luke followed afterwards, each making use of portions of Mark.
The Gospel of John (A.D. 95-100) is a very special case. Sometimes it agrees with Mark, Matthew, and Luke. But in many places it is completely different. Most likely, the author of the Gospel of John knows about the material found in the other Gospels, but he chooses to interpret it all his own way. For example, he sometimes corrects what the other three Gospels say. And what about these corrections? We can describe them thus:
A. There was a strict selection of stories pertaining to Jesus and his miracles. In addition to these the author added some accounts that were fictitious (e.g., John 4 and the Samaritan woman at the well; John 20 and the appearance to Mary Magdalene).
B. John added some long monologues and speeches and presented them as if Jesus had himself spoke those words. Really, though, they are just an expression of the theology of the author of the Gospel, not really the words or the mind of Jesus.We have to be more careful with this Gospel when thinking about the historical Jesus. Some people who write about the historical Jesus won't even cite from the Gospel of John. But I think that position might be going a little too far.