Books like Frank Peretti's, "This Present Darkness," and "Piercing the Darkness" fall into this category. I assume Kathryn Mackel's, "Hidden," would also fit this definition. The powers that be in CBA reason: 1) Angels and demons are real. 2)We don't know how they operate. 3)Therefore, the book is speculative.
What about books based on Biblical stories that contain scenarios not found in the scripture? Are these considered Christian speculative fiction?
Since I lived in New England for over 20 years, I'm aware of the spiritual warfare needed to survive in that area. Frank Peretti's books do not freak me out. While everything may not be 100% accurate, there's a lot of Biblical support for the spiritual battles taking place. Think about the story of Daniel praying, and the glimpse God gives us of the battle between angels and demonic princes.
What other books are considered Christian speculative fiction and why?