I don't think the point of this movie is to go to the exorcism. Instead, it explores medical pathology, religious conflicts, and people's beliefs through the incident of the girl being possessed by evil spirits. Some things can change the beliefs of some people - a girl who doubted God when she was possessed; a female lawyer who shakes her atheism when she is deeply involved in a case.
Did God choose us to fool the devil? Or is the devil and God playing fair, and man is the pawn to let them win or lose?
In this movie, I think God didn't win, and the devil doesn't necessarily lose. It was the spirit of the girl's sacrifice that made her a saint. The female lawyer is no longer domineering, and faces her life religiously.
This movie reminds me of another dark movie "Constantine", it said: God and the devil are actually fair, they let you choose which side you want to cast.
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