It's kind of like saying a-"bigfootism" isn't a religion, but many "bigfootists" are religious, if you get what I mean (and even if you don't, it's still like saying that). I mean they might not call themselves religious, but they behave like they belong to a religion in the way that they are superstitious, are convinced of some conspiracy theories, which shape their worldview, or believe that all religious people need to be converted to atheism (and therefore "preach" atheism just as a Christian might preach their religion to others).