I did some research in the bible after watching to movie and found all the 6 demons in there which were mentioned in the movie. The 6 of them were
(1) The demon who possessed Cain who then murdered his brother Abel
(2) The demon who possessed Nero who became probably the most evil
emperor of Rome.
(3) The demon who possessed who Judas who then betrayed Jesus.
(4) One of the demons who possessed the man mentioned in Mark 5:10,
Legion was it's name. There were many demons in that man.
(5) Then there was belial, said to be an arch demon.
(6) Lucifer himself, aka the devil or Satan.
Personally, I do believe in demons and evil spirits and possessions. But I guess it's best not to offend or dwell in in such things as these. After watching the movie, I understand better why bad things do happen to good people. It's more disturbing than scary, and very thought provoking as well..