There are degrees and levels of fiction. But it's all still fiction. And I understand that you disagree, because you are a 'believer' in the fiction of "objective reality": a realm of existence that cannot be experienced or verified by any human, but that you are absolutely certain you know to be so. Same as the theistic 'believer' believes in the fiction of a perfect deity: also a realm of existence that cannot be experienced or verified by any human, but that the theist is absolutely certain they know to be so. (Not all, of course, but many.)
I would say that objective reality is imperfectly experienced by humans and that it is verified by many different processes. And it is quite different than being 'fiction'. The equivalence with religious beliefs is, to me, clearly bogus. We *can* verify the existence of atoms, and of dark matter, and of other galaxies in ways that we simply cannot verify the existence of deities.