I just started watching the movie, and can't comment on the whole thing just yet. However, the beginning of the movie contains no new arguments or cases that haven't been well disputed already.
As a Christian layman I can easily debunk one of the most oft repeated "facts" that I have seen thus far. Nowhere in the Bible does it declare that Jesus was born on Dec. 25th, if you find it I will give you every dollar that I have. The fact is that once the Church was established as the official religion of Rome, the church leaders decided to celebrate the birth of Christ on the previous date of the pagan celebration of the winter solstice.
Anyone interested in getting the other half of the story can check out this link
Investigating the Similarities between Jesus and Pagan Figures
or this one
Christ Myth Refuted. Did Jesus Exist? A Christian Response
So in the spirit of challenging your strongly held beliefs I also encourage anyone interested to visit one or both of these links, as I will continue to view the Zeitgeist movie and challenge mine.
So far though I am enjoying the production values of the movie quite a lot.