There may not ultimately speaking be a self, but there is this ever-changing heap of Five Aggregates. That's the "soul," the psyche, the spirit, the gandharva (Pali gandabba). It is not what we think, but it is not nothing either.
There are -- apart from form or our bodies -- feelings, perceptions, mental formations, and consciousness which we cling to as "self," as our abiding identity, as our core ego.
And that amalgamation or composite self can become "possessed," taken over by powerful and negative forces. There are spiritual rules for this, freewill, and the bad spirits have to be invited in, but they trick their way in.
|Bon shamans, lamas: demon dance|
We are not ourselves, but even the impersonal self we cling to -- which feels like it is me and mine -- can be lost to others. Theravada monks will chant parittas or protective chants, and Vajrayana lamas will do rituals and ceremonies influenced by Bon shamanism and black magic of Tibet, Bhutan, and Nepal. Mongolian shamans may have to be brought in.
Whether it's all psychological or much more, who can know? The victims and those around them feel it's objectively real for the paranormal phenomena that happens around the possessed. Something's happening. And something happened to a child in the U.S. that led to this film being made. There is a supernatural (which is actually just natural in Buddhism) world and we remain blind to it most of the time.
Newly discovered behind-the-scenes footage!