We have lost our history of words. The word demon comes from Latin which comes from Greek which is linked to Hebrew concepts of spirits, messengers, idols, and gods.
Socrates wrote about having a guiding spirit which counseled him. Plato discussed these spirit entities with a secular focus.
We moderns are uncomfortable with the idea–an invisible world of possibly invasive personalities?
The English translation of the Bible draws clear lines between angels (malak messenger) and demon (daemon spirit, idol).
Do we think that in our material world these have dissipated like a primordial mist?
Or are they still there? Trapped unless we listen? Perhaps we need to revisit Socrates and look closely at the way evil moves in the world. And good as well, depending on the power of the voices in our heads?