Is this article discouraging? Someone asked this question in the comments and he responded with this: -->"This is interesting. What’s your take on why stories like The Shack and Heaven is for Real sold millions… they seem like personal Christian stories to me" -->"If a book has a spectacular story and written really well, it can sell great!
By the way, most novels (including The Shack) have characters and themes based on real life stories."
http://www.stevelaube.com/christian-memoirs-rarely-sell-well/