I see the Christianity.SE as a way to learn more about Christian history, doctrine, theology, and practice. Aspects of Christian culture, such as Christian fiction, should go in the Literature.SE or elsewhere on the Internet.
However, this really depends on a case-by-case basis. Maybe the question is really concerned with the truth of the Christian practice that is portrayed in a work of literature and wishes to learn more about it. It does not have to be Christian Fiction, specifically, because any fiction that has Christian practice can pique the reader's interest.
On the other hand, I think questions about fiction should be limited or avoided, because fiction is supposed to be just that: fiction or made up.