Sort of like being gay, then: if you support it then it's not a choice, if you dislike it than it is a choice. I wonder how many other things there are which function in the same manner ...
People don't choose belief or lack of belief, or agreement or disagreement with any idea, unless they're trying to brainwash themselves.
I think the answer depends on who you are. It is a choice if you don't believe in religion. Its not a choice if you are religious.