That's a pejorative way of asking it, isn't it? We have a lot of emotional baggage attached to the words 'made-up' and 'fiction.' When we hear these words, we immediately think false! Add those words to the stories about Jesus in the New Testament and you have a religious war on your hands.
I do not think the Gospels are fiction, at least in the modern sense of the word. I do not think the Evangelists (those who wrote the Gospels) simply made stuff up about Jesus. I do, however, believe they 'creatively' expanded the original story of Jesus to speak to their current social problems. And I think they did so with a dialogic agreement between themselves and the audience. They were expected to re-tell the story of Jesus to fit their own demands. (I give this a fuller treatment in my book.)
We live in a cynical age, when we deride the Evangelists for doing this (and thus either surrender to atheism or retreat to a fundamentalistic rejection of historical criticism) while gobbling up the latest retelling of the same Hollywood trope. Is there room to accept the Gospel accounts not as historical accounts, but as providing a living voice of Jesus?
I think so. I hope so. But that is not the scholar's job.
For those of us engaged in the field of Gospel Criticism, we investigate how the Gospels were written, not what the 'gospel' is. In a previous generation, after historical criticism started to take hold in Europe a few centuries ago, German scholars (in an undoubted attempt to hold on to some form of orthodox Christianity) came to see the connections between the Synoptics (Mark, Matthew, and Luke) as a telltale sign of a previous source. They called this source 'Q,' after the German word for 'source.' Many New Testament Scholars today still hold to a non-existent document that is a collection of sayings and may or may not include accounts of the Virgin Birth and the Resurrection. This is a rather conservative position and gives hope for those trying to identify the so-called Historical Jesus while maintaining a greater historical truth to the Gospels.
But a growing number of scholars (notably Mark Goodacre and Francis Watson -- and myself) argue for a different origin. 'Mark' wrote first. 'Matthew' used Mark, but expanded it. 'Luke' used Mark and Matthew and attempted, as he says in his prologue, to sort the issues out. I contend 'John' used Mark as a primary source and creatively turned Matthew, Luke, and maybe another source into what we now know as the Fourth Gospel.
I argue Mark is the only possible eyewitness to Jesus, but this doesn't stop him from using the story of Jesus to speak to his present needs. His seemingly barebones Gospel doesn't tell the history of Jesus, but his story of a world challenged by false messiahs, Jewish and Roman civil wars, and apostasy of those who waited in vain for Jesus to return. Of course, Mark answered this by suggesting Jesus really did return when Jerusalem fell in 70 CE.
Matthew did not need knowledge of the historical Jesus to draft his Gospel. The Sermon of the Mount could be pulled from Jewish interpretations of Deuteronomy. Since Matthew is writing to preserve continuity to the Jewish community, basing the rule for the community on Deuteronomy would be necessary and theological safe (Paul did it).
Luke is a special breed of writer. He uses Mark and Matthew, but adds in well-known parables. Did these parables descend directly from Jesus? Who knows, but they are Luke's stories meant to speak directly to why he is writing his Gospel. His Gospel is one answering the economic plights of his day.
The expansion Matthew gives to Mark's original story does not necessitate a historical Jesus. Luke and John as well. We can trace these expansions by later authors and provide real answers without pretending the writers used historical fact.
Does this mean the Gospels are just fairy tales? Hardly. Learned individuals wrote these works to communities with ancient literacy rules requiring such innovations. Further, since the Jesus-community did not stay the same, never faced the same contexts, and grew the story of Jesus had to change and had to answer this influx of novelty. And that's what the Evangelists did. They took the living voice of Jesus, decades after the life, death, and we hope resurrection, to provide for their community a living word, ever present, ever hopeful.
Perhaps that is why I am so melancholy about modern American Christianity. We have forgotten the living voice of Jesus and instead turn to the letter that kills, demanding a rigid historicity when a fluid story is what brings life. We are so stuck on the Jesus of our hardbound book filled with dead trees and lifeless ink we forget the Jesus who is supposed to be alive and moving us forward.
We turn to see what we think Jesus said about this or that (usually homosexuality or the latest political football) without wondering what the story of Jesus would say to our entire reality. Could we replace leprosy with AIDs? What about the Samaritan with LGBT youth? What do you think the story of Jesus would say to those churches divorcing themselves of the Boy Scouts for offering a place for LGBT youth? How do we talk about our Christian responsibility to the environment or the inclusion of scientific fact in our theology?
As Christians, we should rediscover the living voice of Jesus rather than resting only on dead paper and dried ink bound by animal flesh. What is the story of Jesus saying today?