While on this blog I have tried to mention the good aspects of Torah. but the religious world of Judaism is sadlly is filled with demonic spirits.
Spirits are very good at making up false religions and appearing to people in the guise of some tzadik. [People think they are safe by listening to false spirits, but then they fall suddenly.] ]
Islam is a good example of a "familiar spirit" that appeared and gave a very complicated mixture of truths and falsehoods.
Demon spirits mislead people. They make people feel good. People want spiritual things, so the false spirits take advantage of this.
The spirits can also come in through a family tree. So even if you have never been involved in any familiar spirits, still they can come in through the fact that somewhere in the past their ancestors were involved in them.
This mainly came into Judaism through the events of the Shatz, but it continue in different forms until today. The best thing is to avoid the religious world since the familiar spirits there can come into a person just by being in the same synagogue.
[Some examples of demon spirit inspired things: Yoga, astrology, modern music, mysticism, psychology etc. That is spirits reveal true things in order to get people involved bad stuff.]
The trouble with all this stuff is that it involve spirits from the Dark Side, and in the Torah most of this stuff gets the death penalty. So even if people are doing their occult necromancy in the name of the Torah still that does not make it OK.
The tendency of philosophy has been to deny all metaphysical phenomena, but that is not my approach. I go rather with the Rambam Maimonides approach which accepts Metaphysics but does nothing to discern between the Bright and Dark Sides.
My approach to these issues is that it is hard to discern. I would say most spiritual phenomena are from familiar spirits and not from holiness. But that does not mean people with familiar spirits do not have vast powers and knowledge of the future. Rather they do, but it is not from the Bright Realm.