Possession

Possession: Mental illness or Demonic attack. What's your view? I have experienced a lot of things that people would say I was possessed when in fact it was only my bi-polar and I wasn't on meds at the time. Also what if you don't believe in god or the devil and you actually become "possessed" by an entity? Would christan prayer really help? Demons come from many religions. So whats the right way to do the exorcism? Who knows. Is it just mind over matter, for example if you believe in something so much does it in fact become real? What are your views?