Consider the idea of spontaneous genesis of life, as used to be belived. What strange kinds of life might arise from modern substances? What kind of vermin would a landfill produce, or an oil spill on the ocean?
A demon who isn't some hideous creature bent on consuming souls, bu is, in fact, a likable chap who enjoys having pleasant chats with people - trying to talk them into becoming his servants.
The Church of the one true God guards a terrible secret: Their God is dying. He is kept within a tank, steamworks forever pumping to keep him alive, clockwork engines forcing his laboured breathing.