I think that's very misleading. What would scare the Christians even more would be proof that there was no human being at all behind their doctrine of a divine Jesus. Contrary to dejudge and others, it is evident that there is a necessary human element in the Jesus story, that God sent His son to live among men, so that we might be saved, and so on. If there was no human Jesus at all, that doctrine falls down.
Unlike the mythicists, the Christians simply can't reconcile themselves to the idea that Jesus was a purely metaphysical being living in a sub lunar never land. That makes nonsense of every part of their Christology.
You do know that some people labeled "mythicist" also hold there was or may have been a historical Jesus, right?
David Strauss, Sir James George Frazer, John M. Robertson, John Remsburg, and GA Wells' current mythical Jesus of Paul + not crucified Jesus = Gospel Jesus are the most obvious examples of this.
As I have pointed out before the 1982 and 1995 editions of the International Standard Bible Encyclopedia expressly state that "This view (Christ Myth theory) states that
the story of Jesus [NOT the man himself] is a piece of mythology, possessing no more substantial claims to historical fact than the old Greek or Norse stories of gods and heroes..."
Even Ehrman defines the Christ myth as saying "no historical Jesus
worthy of the name existed" ie even if there was a flesh and blood Jesus "he had virtually nothing to do with the founding of Christianity" more or less the SAME definition John M. Robertson used back in 1900.
"The Jesus of Nazareth who came forward publicly as the Messiah, who preached the ethic of the Kingdom of God, who founded the Kingdom of Heaven upon earth, and died to give His work its final consecration, never had any existence. He is a figure designed by rationalism, endowed with life by liberalism, and clothed by modern theology in an historical garb."
(...)
"The mistake was to suppose that Jesus could come to mean more to our time by entering into it as a man like ourselves. That is not possible. First because such a Jesus never existed. Secondly because, although historical knowledge can no doubt introduce greater clearness into an existing spiritual life, it cannot call spiritual life into existence. History can destroy the present; it can reconcile the present with the past; can even to a certain extent transport the present into the past; but to contribute to the making of the present is not given unto it." - Albert Schweitzer
As I said before most of Christianity has locked itself into a Myth, madman, messiah dynamic. If Jesus wasn't a [philosophical] myth and messiah is out because of all its supernatural baggage then all they have left is madman ie Jesus as the 1st century equivalent of David Koresh or Charles Manson.
Christianity is not just dependent on Jesus existing as a human being but being what the Gospels claim he was.
Why do you think people are so driven to prove as much of the Gospels are history even if it makes no sense?
Why else do a crap load of ad hoc handwriting to get Matthew and Luke to agree?
Why else attempt to push Herod the Great's death forward to 1 BCE?
Why else ignore all the factors that show the Sanhedrin and Pontius Pilate trials are most likely total fabrications?
Why else imply the evidence for Jesus
is as good as that for the moon landing or Holocaust?
One doesn't do all that if one are simply trying to say their founder existed as human being. One only does all that if then need to show that
the story of their founder is more historical then the Penny Dreadful-Dime Novels starring known historical people like Buffalo Bill, "Wild Bill" Hickok, and Annie Oakley.
For most of Christianity the story of Jesus is as important as the man himself.