This is a reread, which I don't usually count towards read counts...except when I do. "Though this be madness, yet there is method in it."
There's this interesting trend among the sff books of the 80s and 90s (lets say the 90s runs a bit into the 00s for the purposes of this conversation) that were written by women of taking on big questions under the guise of formulaic genre. Not all formulaic books do this--although perhaps more than anticipated--but I have found that books written by men are either high- concept OR conventional genre, while books by women tend to incorporate the concepts into the genre. The exceptions to this rule, the women who write high concept like Le Guin, Russ, Tiptree (whose male pseudonym complicates matters) are also the ones who have become canonical. And then there is Butler, who is so much a class by herself that I don't even know where she goes.
Shinn has written a science fiction police procedural romance and hews quite strictly to the genre conventions of each--which already makes this book an interesting mash-up--while also trying to have a conversation about the portrayal of religion in sff. This isn't her first book about religion in genre fiction; the interested reader is directed towards the Samaria series in particular, but she is less interested here in the crafting of religion and more in its impact. A different book would probe at questions of devotion, of ritual performance, of the aesthete versus the ascetic. Shinn's story leaves little space for that and even less space for forming any conclusions about them. This is wise on Shinn's part - the genre conventions of the romance do rather stack the deck against a celibate order, after all, and Shinn is more interested in validating religious experiences of multiple varieties...provided they are grounded in love and not violence.
This approach of using the formulae of the genre to break it carries over into the current generation of writers, although they are far more deliberate in upending familiar tropes and are less willing to bow to convention, preferring a messiness that captures the kernel of the genre and jettisons the trappings that can limit it. The problem with Shinn's work is that you can get through the whole thing without having to actually chew on the question of religious devotion and the role of God. Although whether that is the book's problem or the reader's is, well, an exercise left to the latter.