50 years after its original release, The Exorcist still amazes and terrifies movie fans. William Friedkin's horror classic, featuring a young girl, Regan (Linda Blair), possessed by a demon, is simple in its concept yet richly layered in its execution. It continues to attract new admirers to this day. In this regard, the film's ending is no different: the demon is expelled, and Regan and her family are free to live the rest of their lives. However, it's so densely packed with metaphors and symbols that critics have been debating its meaning since the film first graced cinema screens.
Source：https://www.cbr.com/exorcist-ending-explained/
