"Actually, Josephus in particular has pretty well been shown to have his writings added to by a later revisionist who was desperate to have some historical mention of Christ. You can look up that argument on your own."
Ok for the sake of this conversation lets give you that one. Now what about the rest who wrote about Jesus?
"Each datum in a collection of information stands alone and either is true or it isn't. Attempting to infer truth of some parts because the others have been show to have some historical basis is an egregious logical fallacy."
But it is used in courts every day, and considered good evidence.
"Recently, an archaeologist found what is now generally accepted to be Troy. Does this mean that rest of the story about Troy, including the part that the Greek gods played in the war, are true?"
No. It can't be denied their beliefs in their Gods didn't play a role though. The original claim was, "Virtually every page of the gospels were plagiarized from earlier pagan myths." This statement isn't true. Not evey page was "plagiarized from earlier pagan myths." Statements from the Bible can be proven, and thus aren't myth.