Fiction requires conflict and characters that are something more than cardboard cutouts. Characters must be less than perfect and should undergo some change from the beginning to the end of the story. That is, the events they face should alter them, for good or ill.
Oddly, characters in too much of Christian fiction turn out to be black or white, with no grays, and the good characters tend to be wholly good and bland and even the evil characters are either thinly drawn or not so awful. Will we ever see a Hannibal Lechtor in a Christian book? We see such people in the Bible, but the fact that something is done in the Bible seems not to matter for Christian fiction. This blandness and lack of true conflict or real people is so unlike the people in the Bible, who are alive and fully defined. The biblical authors showed us their characters with all their warts and flaws and cringe from nothing. The chances of getting a piece of fiction published by a Christian publisher which shows the life of Lot, for instance, or Jephtha, seem slim. Lot lived in Sodom, offered his daughters to a mob to be raped and later committed incest with them. Jephtha sacrifices his daughter as a burnt offering. In fact, I think most of what happens in the book of Judges would make most Christian publishers uncomfortable. Frankly, too often real life seems to be uncomfortable to a lot of Christians, not just publishers. Too many Christians are afraid to confront others and themselves as they really are and instead behave as Elinor Rigby, the woman in the Beetles song who kept her face in a jar by the side of the door. Apparently she put it on whenever she went outside. A lot of Christians seem to wear masks, both in public and even, sadly, when they look in a mirror.