Demons–in the supernatural horror sense of the word–may exist, in real life, if other kinds of discarnate entities exist. Nature seems prone to creating each organism with something like an opposite, or at least an opposition. Nature is founded on balance. If an ocean fish swims about as an aquatic herbivore, harmless to us, we presume that somewhere there are sharks. If there are flowers that lift our spirits with their beauty, there are also some that poison us when we touch them. There are predators in corporeal nature; there are assuredly predators within incorporeal nature: in the realm of spirits, if such a realm exists.
If souls or spirits survive our deaths, they will carry certain of character fixations into the afterlife. Men who are predators in life may be predators after death. Some may be the basic template for the creatures we call “demons”. Mortal men of cruelty might become immortal spirits of cruelty. Perhaps, as in some Hindu lore, some discarnate spirits may be parasites feeding off human life energy.
How could the purported spiritual realm be complete without predators? Surely if such a realm exists it has its own natural, if subtle, biology; its own “food chain”, its own ecology. It’s not a case of magic–but of some unknown ecosystem existing in a realm thus far invisible to us. Unseen–yet as natural as snails and birds and bacteria…and sharks.