Over at the Faith*in*Fiction discussion board there's been discussion about themes in Christian books. One of the challenges we face is keeping our characters authentic. By that I mean that they are honest about their struggles, but also honest about how they deal with them, honest about their faith. I think authenticity in characters can help illuminate areas such as judgementalism, the damage gossip can do, acceptance of people who are different -- all areas where the church doesn't always hold up a shining example to the world.
I guess one of the books that comes to mind, maybe because of the Pope's last days, is In This House of Brede, by Rumer Godden. It's set in a Benedictine monastery in the 1950s and early 1960s. One of the things about this book that I like is that the characters, all nuns, are portrayed as real people, with real struggles. They don't alway like each other or agree with each other, but they love each other, agape love, which allows them to work through their differences. It's not "Christian" literature, but it's a story with characters whose faith is essential to who they are.