There's no direct evidence that supports his existence, only second-hand witnesses. So there's quite some crackpots out there that say he never existed, when it is nigh-certain he did.
Yeah, as it's already been stated prior in this thread, this is very, very dangerous discussion indeed.
Basically, the question "did Jesus ever exist?" is actually somewhat ambiguous, and should probably be rephrased as "did Jesus exist as described in the New Testament?"
It's quite impossible to make the case that there likely didn't exist some individual by the name of Joshua or Jesus or something similar in early 1st century Judea, who developed something of a following. To make the case that Jesus was
purely fictional (as many people would for example make the case that Nephi, son of Lehi was purely an imaginary character of Joseph Smith, Jr.) is not just hard, but pretty much impossible, because even if it would be true, we don't have enough documentation from that era to demonstrate it.
However, many people would probably object to the statement that there existed some individual by the name of Joshua or Jesus in early 1st century Judea, who was born of a virgin, visited by three kings who found him by following a star, raised the dead, walked on water, cured the sick, exorcised demons, fed five thousand people with five loaves of bread and two fish, turned water into wine, was executed by the Romans, fulfilled the Law of Moses, suffered and died for ours sins and by his blood purified our souls, arose from the dead and was the Messiah and the Son of God, glorified the name of the Father, and that whoever takes upon him- or herself his name should not suffer eternal damnation but instead sit on his right side in the Kingdom of Heaven. They'd say that no individual ever existed
as such.
I think Raëlism makes a good analogy here. Do I believe that Claude Vorilhon exists? Absolutely. Do I believe that Raël, who was visited by the aliens who calls themselves the Elohim on December 13, 1973, was taught by these extra-terrestrial beings of their creation of mankind and plan thereof, and was then designated to become their messenger for all mankind exists? Not really...
(Apologies to any Raëlians out there. I was not my intention to make fun or mock your religion, but merely to use it to illustrate an example!)