Don't go overboard.
You have no evidence that "a bunch of fundamentalists" believe that, and I suspect that this film clip was the first time you ever heard anyone say it.
Most serious Christians are fairly well-informed on the very early history of the church. Keep in mind that the post-crucifixion development of church doctrine and history comprises most of the New Testament.
It would almost be more accurate to label the religion "Paulism" instead of "Christianity" if you were talking matters of doctrine.