Unless there's indisputable proof that he was resurrected (And face it, there isn't. Why else is it called "Faith"?), then no serious historian will ever claim that he was resurrected. That's weird. Serious historians agree that Socrates of Athens existed, but I have yet to see any "indisputable proof" of that fact.
What exactly is "indisputable proof", anyway?
Big difference whether a man existed and if whether he was resurrected from the dead. If you're looking for evidence of that having happened, you gotta set the bar just a wee bit higher than if you're trying to figure if a man actually lived.