why not religionism ?

[Belacqua]

Racism is called "racism", but discrimination against a religion is called "xenophobia".
Why is it not called "religionism" ?

I think "xenophobia" can include things other than religion.

It could be against East Asian people, for example, regardless of religion.

But I agree that we should have a word for people who are prejudiced against religion. I sometimes call such people "anti-religion," but that can include people who have reasoned arguments against religion. 

We also need a word for the emotional, bigoted people whose hatred goes beyond reason. People who just get off on their hate. "anti-religious bigot" will do, I guess, but it isn't very catchy.