In evangelical circles, it's pretty common to have a "witnessing" story where they start out as a godless heathen and then come to Christ after some sort of supernatural experience. The bible-beaters tie atheism and satanism together for some strange reason, so it's common to go with the story that demons attacked them because atheists are weak to demonic influence or somesuch bollocks. It's all a crock.
You know the real story? Someone got indoctrinated at a young age, drank the Flavor-Aid at some point and bam, we got ourselves a crappy Paranormal Activity knock-off. These people churn this crap out. Not so much for us, but to sell to each other. To convince themselves that they got it all right and they're privy to the grand truth of the universe. Truth is they have no idea. We have no idea. No one has any idea. They're just talking themselves into something they already want to believe and were raised to believe. That's the much, much simpler and imho much more likely explanation.
Oh I know, I get it. I was trying to be sarcastic.
But I believe that most of these possession stories are reflections of some sort of sexual or physical abuse; sometimes recieved, sometimes done to another person, maybe even witnessed. In the most extreme circumstances of oppression and brainwashing, it could even be just masturbating and feeling guilty about it.
See, in Islam there is no 'devil posession' but djinn posession. Of course there are countless different beliefs in itself but generally, according to believers djinns are another folk created by god before humans and exactly like humans they born, grow up, get marry have children and die. There are good, bad, religious (from every religion), atheist djinns. They do good or bad deeds. They're not of matter while we humans are, which makes them inferior to us. (Obviously we are the best thing ever happend to this universe...duh) They move in incredible speeds etc... Interaction with them is strictly forbidden for humans but djinns also fall in love with humans, have kids and live together all their lives...blah blah
Now, most of this stuff is just simple sleep paralysis because it almost always happens at night. I suffered and still suffer from it time to time, it can be pretty unsettling if you don't know what it is. I had almost everything from floating in the air, hearing the conversations of people from other centuries, in tongues, touching me, pushing me... 'wrestling with beings' in bed, which always feel very agressively and sexually male. (I wonder why,lol.) Think about mostly ignorant, religous people experiencing anything like that. Trust me, it's HELL of a job, mostly impossible to convince the most educated people that it just hallucinating during a natural state. I've tried. It pokes something very primitive.
But if you read about 'djinn incidents' esp. among young people in forums, anonymous stories, you'd see they're almost always sexual incidents. Long story short, if you read all this from a rational point of view with its positive and negative parts, this belief is a key ground to express anything that a human being in an oppressive, religious closed society, household cannot deal with. Be it something as simple as experiencing masturbation or intense sexual desire with a wet dream, half awake.
But the alarming part is the possible sexual abuse these people might be suffering from. This is pretty much like the alien abduction stories. I believe the same thing goes around in the Christian circles under the name of 'devil possession'.
Anything is done to the person or they have done to someone else or maybe just witnessed that they can't deal with under certain circumstances goe out as some 'possession'.