I usually find when people say they want to talk about religion, or when they say they hate religion etc, they usually mean Christianity.

As for all the different types being Christian, I think some of them are only Christian via their own declarations (The Jesus Army for instance) and would not be thought of as Christians by say the Smith family who go to church every Sunday.

P.S. Actually The Jesus Army is probably closer to the Smith Family than the End of the Worlders you see in town, who are the very thinnest end of the wedge.