That's the argument that some have made for the historicity of the Gospels, that if they were not history, then there would have been some people to contradict them.

However, the Gospels were likely written after the destruction of the Jerusalem Temple in 70 CE, which meant that most possible witnesses/non-witnesses were either dispersed or killed.

And would Gospel skeptics have slowed down early Christianity? From the history of a variety of recent cults, and from the early Christians' attitude to those who disagreed with them, I'm sure that such skeptics would not.

The Gospels depict JC as venomously denouncing those who had refused to follow him, and his followers have been more than willing to compete with him there.

And many recent cults have attracted a lot of skepticism in their early years, without being stopped by it. Consider Mormonism, Christian Science, and Scientology.

Mormonism had been viewed as an outlandish cult, and its founder had been killed by a lynch mob, but that did not stop it from growing.

Scientology has attracted no shortage of skeptics over the years, going all the way back to its beginning. Its creator, L. Ron Hubbard, had cured the sinusitis of _Analog_ magazine editor John Campbell, who then introduced Dianetics to the late Dr. Isaac Asimov. Noticing Dr. Asimov's skepticism, John Campbell commented in exasperation, "Dammit, Isaac, you have a built-in doubter." An assessment that Dr. A appreciated.

If skeptics had been unable to nip Scientology in the bud, then would they have stopped early Christianity?

Actually, I think the argument was more along the lines of why no ancient sources ever questioned the existence of Jesus. I think the argument is strongest when we are discussing ancient Jewish sources. Yes, Jerusalem was destroyed, but that hardly destroyed all the knowledge of the Jewish people. Much of their tradition, including references to Jesus, were retained in the works of Josephus and the Talmuds.

Josephus has a few *very* short references that have been much argued over, and the Talmudic references are a few centuries later, and contain such contentions as the belief that Jesus Christ's father had been a Roman soldier.

And I'm not sure if Layman believes that that's who JC's father had been.

Again. The point is that the Jews, although having plenty of reason to do so, do not appear to have ever questioned the existence of Jesus. The Talmud preserved various earlier traditions, including some about Jesus. None of those traditions, however, ever questioned the existence of Jesus as an actual human being.

Would anyone have had any reason to question that there had been a historical Jesus Christ?

If I claim that I have a sister, would any of you people quickly conclude that she's a figment of my imagination?

I doubt it, because people are usually truthful about what brothers and sisters they are aware of having, and because having a sister is not an unusual occurrence.

Likewise, a pagan coming across the early Christian Church would find its claimed founder to seem like lots of other self-styled prophets and miracle-workers, and would find no good reason to doubt the existence of such a person.

The Jesus-myth theory is based on a careful study of the contents of the New Testament and related stuff. I'm not sure that any pagan or Jewish critic would have been motivated to make such a study in such gory detail. So their opinions would have been formed by a relatively cursory sort of reading, in which Jesus Christ comes off as a self-styled prophet and miracle-worker who is not much different from the likes of Apollonius of Tyana.

I'm pretty sure it's now the minority view to date all the Gospels after 70AD. But I'm not going to argue that here so for the purposes of this thread I will agree to assume all the Gospels were written after 70AD.
A notable witness who was apparently still alive was John the Disciple. It is Church tradition that he lived into the 90s. But knowing how skeptical many here are of 'Church tradition' I don't expect to be believed. I have no idea on whether there is other evidence for John's long life: Nomad, Layman do you guys know anything here?

I am quite sure that if John had denounced the Gospels there would have been problems. With skeptics in other cults the skepticism is coming from outside. But if the 'beloved disciple' of Christ himself had denounced the Gospels, I think there would have been serious repercussions.

No early historian questions the historicity of Jesus. Therefore, we must assume his existence to be a fact.

How far can we take this line of reasoning? Matthew tells us that at the moment of Jesus' death, tombs opened, the dead arose, walked the earth, and appeared to many.

Doesn't it seem curious no one else reported such an unusual event? Even the other three evangelists fail to mention it.

And yet, as we have no evidence of any early historian questioning this, must we accept it as fact? Are we foolish skeptics if we doubt anything in the Bible?

As you note, not all Christians reported this event. It does not appear to have been a central tenent of Christianity.

Moreover, we don't have people commenting on the "zombies" one way or the other. If it was reported only in Matthew's gospel, most pagans and Jews would never read it or hear about it.

But we know that pagans and Jews did hear about Jesus. Josephus did. The Talmud did. Celsus did. And they never questioned it. I think those are the strongest indications. I actually agree that no Roman historian was really in a position to question the authenticity of Jesus by the time they heard of him.

The Josephus reference has been criticized as a possible interpolation.

Celsus and the Talmud only knew about JC from his followers, and they were no more willing to doubt JC's existence than most early Christians had been willing to doubt the existence of the deities of Mt. Olympus.

If I claimed that I have a sister, would you people instantly disbelieve me? 'Nuff said.