Demons are parasites. They have physical bodies and they live inside of us: bacterial, fungal, protozoa, helminths. They are the cause of most diseases, mental and physical, and this includes fetishes and other nasty habits and addictions. When people say they have a "craving" for some food, it's not them that is craving it, it's their parasites influencing their mind, to eat what THEY need.
They can manipulate us with hormones and speak to us in dreams. They can cause lust while we are awake, or they can cause nightmares during sleep.
From a spiritual perspective, these beings exist in the 4th dimension. But they do have a physical 3D body and can be defeated.
The ancient method for demon (parasite) removal is fasting, prayer and bitter herbs. And in extreme cases, exorcism.
The modern method for demon (parasite) removal is to take parasite cleanse supplements, piperazine or albendazole, or even the horse paste if desperate. Also fasting.
That is why fasting is part of every major religion. Because at the root of those religions is the removal of demons (parasites) to live a clean and decent life.

The Demonic Parasite Presentation
https://youtube.com/watch?v=1iQF5xv7PXE

The Parasite Pill PDF
https://www.scribd.com/document/613982677/Parasite-Pill