The Scariest

This advertisement certainly must be.   "The Exorcist: Believer" is reviewed as 'authentic' sequel and revival of the original "The Exorcist (1973)", pioneered in 'exorcism', or 'possessed' genre of horror films to date.

It is because of "Believer" plot, to bring back Regan's mother, Mrs. Chris MacNeil, played by Ellen Burstyn, after 50 years, of similar event, circumstance, and victims.  

Half a century ago, in the film history, when released, the original sparked the controversy, whether the subject, the movie itself, should be shown, with even the nature of religious depiction.  And still considered to be the best.  The scariest ?