on the face of it, that is pretty outrageous. Can you imagine trying to teach a Western Civilization class without reference to religion? Impossible.
I suspect there's more to the story, though. There always is. This article said the students were offended by his teaching style:
http://www.desmoinesregister.com/app...=2007709250379
You can be professional and scholarly, without being rude to people's beliefs.