Religions and other cateities as categories
Religions, ideologies and so on are cateities: As self-identified identities, their meaning depend on the actual views of the individual adherent - but as categories, their meaning depend on whatever views held by the person doing the categorizing.
Religism, just like any other focus of categorism is a matter of categorization done by the categorist rather than a matter of what identity is held by the target. Phrases such as "bigotry against a religion" refers to bigotry against people who are categorized as belonging to this religion, not the religion itself: Religions and ideologies are ideas, not people. Therefore, it is not possible to be bigoted against a religion in itself. The phrase "bigotry against a religion" is a bit unfortunate and problematic because it is sometimes be misused in this way.