So Mark's story had to be true because everyone was a (cough) skeptic and certainly would have bothered to take the time and risked the travel to check the facts before converting to Christianity.
1. We know both from the NT and from early christian writings that the early christian communities DID travel and communicate. In fact, this is how the gospels survived. Not only did missionaries travel to various communities, but texts as well. If the early christians did believe their "godman" to be a historical person, no one would have botherd with Mark, or any of the other gospels.
2. In the earliest layers of the community while Mark and Luke were both around, Jerusalem was the center of christianity. Jesus could hardly have gone unnoticed if he really taught, attracted followers, and was crucified. If no one knew him, than Mark would be rejected as bad literature, especially by early chrisitians who, in your view, never believed in a historical Jesus.
3. We know from various sources (Paul, Luke, Polycarp, Papias, etc) that christians did indeed "bother to travel and check facts."
4. There were plenty of skeptics. Paul, a contemporary of Jesus, was one of them, and they were still around when the gospels were being transmitted. And these skeptics (initially Jews but very soon roman authorities as well) could easily have said "this guy was never around." People did travel between communities, and the head church was (orginally) in the very place Jesus died. It's not like we are talking about large place where I guy like Jesus could be missed by competing Jews. The fact that only one wrote about him only means that he wasn't considered important enough to unbelievers to write about.
Unfortunately we don't have a record of anyone checking the facts and converting to Christianity in the first century, so we don't have a case for that.
Actually, we do. Luke explicitly discussess learning from eyewitnesses, the author of John from a disciple of Jesus, Papias from various disciples, and so forth.
As for "checking the facts" ancient histrians from Herodotus to Josephus did this either by writing about personal experience or by interviewing people who were there at the time.
According to 1Corinthian 2, skeptics can't see the truth because their methods blind them, so where does that leave us?
With you misinterpreting 1 Cor. 2. Paul doesn't say anything like what you state above.
Those that believed in myth and magic were most likely the ones that converted to Christianity.
Plenty of the most superstition cultic followers of gods did not convert. And again you miss the fact that, even if everyone was superstitious, the reason they joined cults was because the existence of dionysus or whoever could not be verified. If a bunch of people in Jerusalem and galilee and places nearby are proclaiming what their founder taught and did, and his miracles and resurrection, too many people were around who could have said it never happened. Many rejected him as the messiah, rejected the story of his resurrection, but never his existance.
It sounds like people haven't changed much at all in two thousand years regardless of how superior our methods are today for researching the facts.
True enough. Because people like you don't actually utilize our superior methods of research.