as a Christian, I really don't have a problem with the professor being anti-Christian, as long as he doesn't let it affect his teaching or grading practices, because, like you said DizzyMe, he is entitled to his opinion.
In college, I had a Western Civ professor who was clearly Muslim, and very much anti-Christian. But while that came across in his teaching style, he didn't let it affect his grading. There were a couple times where it appeared that the one openly Muslim student got preferential treatment, but I got my A, so I didn't care.