Bart Ehrman destroys Christianity in under 12 minutes.

[Angrboda]

I thought the reason he gave for his agnosticism was the problem of evil?

I don't think so, in a few debates I've watched he specifically said it was from investigating the bible thoroughly. Although he certainly could have more then one reason.  If more Christians investigated the bible deeply, we'd have more Atheists and Agnostics.

"But after many years of being a liberal Christian, I finally became an agnostic for reasons unrelated to my scholarship ... reason having to do with why there's suffering in the world if there's a God who's in control ... For years I thought about it, I read what the biblical authors said, I read about what theologians said, I read about what philosophers said and I got to the point where 'I just didn't believe it anymore'." ~ Bart Ehrman