Amanda Witmer has written an article for The Bible and Interpretation about mythicism. Here’s how it begins:
In some quarters it is now fashionable to argue that Jesus did not exist! At the opposite end of the spectrum we find the position that every word of the Bible is literally true and that the gospels provide us with an unfiltered historical account of Jesus’ life. This is a false dichotomy rooted in our human tendency to insist on absolutes and true or false claims. Neither position takes the evidence seriously. As it turns out, historical information about Jesus can be found, but sifting through the data requires some work.
See also the excellent post at Unreasonable Faith about storytelling and how stories which may not be factual can still tell us something about how a real, historical figure was perceived, the impression that they made.