I’ll be discussing the merit of exorcisms, and how credible they are- what makes it work and not work, and so on.

The loose definition of an exorcism is the removal or dismissal of an entity (usually malevolent) from the host body, whether the host be a living being (e.g. a human) or an inanimate object (e.g. a rock); the exorcist is the one doing the removing. The classical idea of this is as the cover art for this article and video displays, a religious figure (e.g. priest) being trained in the art of doing so, and being called upon to help. For extensive information, see here.

The reason this form of de-possession works (when it does), is because of two reasons:

1. Self-belief; fate & conviction (even blind convictions) equal energy needed. 
2. A ritual or likewise action/words/phrases that have power to them, generally due to repeated usage. 

It is these two combinations that in most cases help out the exorcist, and NOT “God” or divine intervention (keep in mind that exceptions exist to this rule). See video below for more information: