How do you define religion? Serious question. Many Eastern religions are atheistic, then there's the polytheistic sects, the Universalists etc etc. Or are you taking more of a "religion is whatever I think it is, 'cause I knows it when I sees it" approach?
A religion is simply a worldview about the larger, unprovable questions: origins, god, morality etc.
Religion is a social phenomenon designed to give you certainty about those things, when living with uncertainty is unbearable.
"Secular humanists" do not take anything to be absolutely true unless it can be proven in a logical sense. Theories validated by repeatable scientific results are not absolute truths. They are generally accepted, and are assumed to be true for practical purposes, but not for philosophical purposes.
As for snark about Christianity, how many people have made dismissive "your invisible friend in the sky" comments about it, and there have been no repercussions? Answer: a lot.
If I seriously expressed a belief in Enki, would you not be dismissive or consider me the slightest bit loopy? That Mesopotamian pantheon was a religion that a lot of people (relatively speaking) presumably took seriously for a long time.
If Scientology, with Xenu and volcanoes and reincarnation and all that, had been started as a cult during the Roman Empire, do you think it would be broadly considered a cult today? Or would it be accepted as a religion -- a dead or a minor one perhaps, but a religion nevertheless?
If I'm supposed to take your invisible friend in the sky seriously, why is that? Why should I take yours seriously and not the Muslim God, specifically the version who wants muslims to displace (or possibly kill) all Jews and take back Israel? Why yours and not Hinduism or Buddhism, nebulous conglomerations of all sorts of beliefs that can mean almost anything to anyone, to the point where people can't really agree whether some versions of those religions even involve a God?
If your contention is that I should take seriously a lot of mutually exclusive belief systems that all proclaim to be the truth (or at least the path to truth), I don't really know what to say to that.
If instead your contention is that I should take all religions seriously, because they're all social clubs that discuss allegories and are only trying to get at the truth, rather than taking things asserted in the Bible or by the Church as absolute truths, then I'm perfectly willing to go along with that. However, then religious tomes and religious doctrines cease to have special significance, and you have to acknowledge for instance Nietzsche's works as having equal standing. Religions then become glorified book or philosophy clubs that don't stray beyond at most a few specially chosen books. I have not yet encountered someone I'd call "religious" who can stand the implications of this religion-as-an-allegory concept, no matter how much they claim that's how they view religion. It always turns into a "my allegory is better than [random other allegory] because mine says it's better", at which point it's no longer an allegory; their religion has been elevated above all other religions and all other philosophies and myths, for no supportable reason.
