PW says Christian mystery–in the classic sense–is a tough sell.
Maybe I’m missing the point, but there’s a lot of "modern" Christian mystery/suspense on the shelves. Pretty much every publisher who does fiction has some or has made a concerted go of it. Maybe there isn’t a lot of classic mystery, but is there much classic anything? There’s a good heap of cozy mystery.
I don’t know. Is it harder for "classic mystery" than for other classic genres among all the modern ones?