The gold standard of a "bad religion": the Aztec religion
Islam is a religion, and it's also evil, unjust, anti-liberal, and dangerous. See? Was that so hard?
1) "Religion" is not necessarily a good thing; so why do we feel the need to deny to Islam that rubric?
2) A thing can be X, and also Y and Z -- i.e., Islam can be a religion and also an evil dangerous totalitarian supremacist expansionist organization.
3) The West has been regarding Islam as a religion for approximately 1400 years, even long before political correctness became dominant and mainstream. It is hard-wired into the Western cultural consciousness, "correct" or "incorrect". Western observers have been doing this because Islam is saturated from top to bottom with the claptrap of religious rituals, artifacts, symbology and language.
4) I prefer the tack of trying to get across the message that Islam is a totalitarian culture, without denying it is also a religion; or, if one must, a totalitarian religion -- or, better yet: a totalitarian religious culture.
5) We have enough difficulties waking up our fellow sleepwalkers on this issue, without having to try to tell them to do yet another unfamiliar dance-step.
There. Now we can spend our time on more important things.
"Islam is not a religion": one of the mantras of the anti-Islam movement