tracer- one of the mentions of JC in Josephus seems to be somewhat in doubt. The Oxford History of the Bible World calls it 'controversial"- but does not reject it entirely. The passage goes “About this time there appeared Jesus, a wise man, if one should even call him a man. For he was a doer of striking deeds and was a teacher of such people as accept the truth gladly… When Pilate, upon hearing him accused by leading men amoung us, had condemned him, those who had in the first place come to love him did not give up their affection for him. On the third day he appeared to them, living again…” (Antiquities 18.3.3). Perhaps this passage is evidence, but it is 'doubtful" evidence for several reasons.
However, in AD62, James (JCs brother) was stoned to death upon orders of AnanusII. Josephus mentions this incident, and states that it was “James, the brother of Jesus (who they call Christ)” who was so killed. (quote not exact). AFAIK, no-one questions the authenticity of this, rather offhand mention of JC. And this was some 30 years after JC death. It is a little hard for an imaginary man to have a brother. I suppose James could have been “imaginary” also- but if so- what were they throwing rocks at? Of course- this is no proof at all that JC was the Messiah, worked miracles, or returned after 3 “days”. So- if one does not beleive- there is no problem in saying some charismatic “backwoods rabbis” story was blown out of proportion, and turned into the Gospels.
The next evidence for the real existance of JC is negative- but a pretty strong negative. During the Persecution, the Romans were desperate to do anything which would invalidate this new religion. They had the records of such things as executions, even by provincial governors. Thus- if the records did not show any record of Jesus- they would have said so. Even if the records did not exist (destroyed? Shredded?)- there were lots of folks who were alive in AD70, and were also around when JC was preaching- and the Romans did not trot out some aged Samaritan who said- “I was around in those days- and i never heard of no ‘Jesus’”(and if the Romans did not want to do so, I am certain that Ananus II would have done so instead). The Romans made, AFAIK, no attempts to discredit Jesus as a real person at all, in fact, the Roman Emperors spoke of Him as if his actual existance was not a bit in doubt (somebody posted some great quotes on this, in an earlier thread, so see them).
Finally, to “argue from authority”- no reputable, unbiased scholarly source doubts JCs actual existance. I know many tire of me using Isaac Asimov- but this Secular Humanist, Atheistic, polymath of Jewish heritage- had no doubts. Kenneth C Davis, in his rather skeptical “Don’t Know Much about the Bible”- posits no doubts about THIS. The Oxford History of the Biblical World- a very skeptical but scholarly and authoritive book- not only poses no real doubts- but states with authority some small portions of His “biography” as actual history (including His execution). They do go on to say “Aside from these few conclusions, neither the chronology, nor the central message of Jesus’ teaching, nor the reason for his crucifixion can be given with certainty.” Thus, for the staff at Oxford- the historical existance of Jesus is a “certainty”. Lastly, Cecil himself agrees.