I can definitely think of a few authors who write about non-Abrahamic religions and spiritual practices, but the majority of those seem to fall into fantasy or science fiction. Not that this is a bad thing, but where are all the real-world stories featuring characters whose spirituality is vital to them?
Most of the books I’ve read fall into three broad categories: angry ex-religious/agnostic/atheist; currently practicing an Abrahamic faith (mostly Christianity); or no mention at all. There’s a range within the first two categories. With the ex-religious, it’s usually of the aforementioned caricature variety, but there’s some wiggle room. With the second, it’s anywhere from casually mentioned to preachy.
I’m not saying other books don’t exist, only that they’re much harder to find. I’m a population of one, so I obviously have not read every book in existence and can only offer anecdotal evidence based on my reading history.
Since I’m not one to shy away from offering unpopular opinions, here’s another one: If you haven’t experienced something, do more research before writing it. Don’t make assumptions about the influence of religion and spirituality, and definitely don’t project your own experiences onto queer folks if you’re not one of us. You can’t simply translate one thing into another, and queer lives and bodies aren’t your playground for working out your own issues.
(As a side note, I think one of the most disturbing things I’ve read was a couple of MM/gay romance authors talking about the reason they write being out of “pity” for the poor gay men alienated by Christianity. I mean, did these self-identified non-queer folks realize that some gay men are, in fact, Christians? And some didn’t grow up with that kind of hate? And that there are queer folks who aren’t gay men and who also experienced trauma from religion regarding their gender and/or sexuality? It was...weird. Please don’t do this.)
At the same time, don’t be shy about exploring things outside of what might be considered more traditional/familiar religions. There’s a whole world out there, most of which is less traumatizing than fundamentalist Christianity.
For my part, I will still explore the things I’m most familiar with when I write. But I’m going to be on the lookout for more spiritually/religiously diverse books.