I've read a couple of "inspirational" romances (apparently, that's a codeword for "Protestant Christian") that were okay, if a bit on the mild side for my tastes (which I expected). I didn't find them cloying or preachy. Comparing them with the "supernatural" romances from the same publisher, which portrayed witchcraft in a way that made me want to throw the books against the wall (I refrained; e-ink doesn't survive wall smashes nearly as well as paper did), I was left to wonder if the Christianity portrayed was as phony and annoying as the occult activities.
(Probably not. There's a lot more public awareness of how Christianity works.)
After trying a couple of them, I avoid them. I might read one by recommendation from someone I knew, but there is nothing about "this book has Christian values as a major theme" that I find compelling. I'd expect that at best, they're good stories based on a moral system I don't share and find sometimes disturbing. At worst, they're preachy fear-mongering designed to convince some Christians that the world is doomed if everyone doesn't convert tomorrow.
I wouldn't mind reading one--but "this book is designed to appeal to Christians" is a strong negative for me. That puts it rather below westerns and YA sports novels on my "likely to read on a lark" list. It'd have to have something else I found highly appealing for me to consider reading it.