We all have seen in our life someone who suddenly started behaving very much unnatural. They get angry with close ones, became furious, hurting everyone. There are some more symptoms found like they forgot their self entity tell their different name even their voice also changes to someone else voice. Then definitely we understand he or she is being attacked by the evil soul on them. An outsider entity took control of him or her. We saw in movies that some expert people can pull out the harmful spirit from them. Whatever their way, religious view are they are called Exorcist in general and the process in which they make free the victim from the black spirit that is called Exorcism.
Exorcism has been practiced from ancient time in every religion view. From Catholic to Hindu, Muslim to Buddha. Before 1000 BC in Atharva Veda we can find Exorcism with other Dark magics. Old Testament also shares on the process of Exorcism to make people free from Evil spirits, misfortune and illness. Jesus also taught Exorcism (power against uncleaned spirits) to his disciples. Even he made many famous exorcism. He cleansed seven devils from Mary Magdalene. Islamic Exorcism also meant to free human mind from jinn or Qarin's the evil desire. To overcome the possession of Saytan.
God help them who help themselves
If we study the exorcism process and technique in various religious beliefs we can find that this proverb is true for Exorcism too. Thought insight the process is to make victim's inner spirit strong such as he or she can fight his or her own battle. Whatever is their inside they must have to fight and make them to leave him or her definitely. An Exorcist passes the power insight his or her real self. He or she must have two strong enough to make himself or herself freely and kick out the black entity from them. Almost every person in the world possessed some religious belief in themselves. So it is a traditional method to take this advantage of their beliefs to nurture courage and confidence in them. Generally we see people with low self esteem attacked by outsides spirits need Exorcism.
In scientific view it is demanded there is nothing about ghost or devil in the spirit possession. These are the case of multiple personality disorder. When man started to think himself or herself as some different identities. In such condition they gain many abnormal activities like very strong power in a weak woman, bad slang language unnatural to his or her behavior even they talk in some language they never know.