So, what IS the interpretation of references to demons, if not literal demons?
The liberal theologian sees Scriptural references to demons as actually referring to diseases - sometimes physical, but often mental: diseases like epilepsy, schizophrenia, or depression. And if a person is healed of that disease, the "demon" has been "cast out."
Now, that's coming from a modernist worldview that is seeking to reduce pre-modern conceptions to merely "natural" (rather than "supernatural") explanations (and some liberal theologies do away with the notion of a personal, sapient God, too!). BUT, since we're interested in playing tabletop RPGs where magic and the supernatural commonly appear, we aren't interested in this approach. In fact, we can SUBVERT it, and REVERSE it.
See, I titled this post "Diseases Are Demons," not "Demons Are Diseases." What if we conceptualize the diseases and maladies in fantasy game settings not as pathogens or psychoses as we moderns understand them, but as actual, personal, sapient spirits of malevolence and illness? That schizophrenic over there? His psyche is regularly invaded by a demon. That epileptic? she's assaulted by malign spirits. That leper? A devil dwells within his flesh, rendering it dead and white.
|Deicide - In the Minds of Evil|
Given that assumption, it makes a GREAT explanation to how healing magic in RPGs work. See, it's often divine magic - channeling the power of a deity to cure disease and illness. But, if diseases are demons, what's actually happening is an EXORCISM. This is COOL!
So, next time your party comes across an individual suffering from "scurvy," emphasize that she is suffering from Scurvy - an infamous demon who emerges from the deeps of the ocean and drains the vitality of its victims! Watch your players start trying to exorcise it with salt, holy water - and perhaps limes!