I find it interesting that "Sinner" has been described or categorized as both fantasy and horror as well as science fiction. Personally, I consider it to be science fiction, although it's not like I take issue with it being classified as science-fantasy or horror SF. I've never been one to play the "what genre is it?" game or its first-cousin, the "that's not such-and-such genre!" blood sport.
Genre labels are wibbly. That's my line, and I'm sticking to it.