One of the breakout sessions I attended was about the 2007 Zeitgeist: the Movie, an Internet movie that supposedly demonstrates that Christianity was derived from other pagan religions. Personally, I could care less about the movie itself which is highly conspiratorial but I have heard that charge from a number of atheists, and always wondered where they got that idea from. I actually heard Michael Schermer make this claim in a debate about 7 years ago.
To say that Dr. Mark Foreman countered the argument is an understatement. He bashed it, stomped on it, beat it senseless and and buried it. I don’t think I have ever heard an idea so roundly defeated; I actually felt a little sorry for people who have believed it.
Basically the filmmaker, and other who have make this claim accept very shoddy old scholarship done by skeptics who cherry picked ancient mythologies. Not only that, but many of the supposed parallels are based on popular notions about Christianity (like the Dec.25th birthdate of Jesus) rather than what was actually written in the text.
In many cases the supposed similarities are really wordplays and not actual similarities; and more often than not they are only similar in the imagination of the movie maker. Some of the supposed events the Gospel writers are claimed to have ‘borrowed’ weren’t written about until long after the the Gospels were. There was more, but this gives you an idea of how roundly the idea was dismissed.
Overall it was a pretty concise piece of scholarship.