If director William Friedkin intended to put onscreen evil in its most vile, shocking and visceral form, he succeeded.  Decades after the demonic dust has had time to settle, The Exorcist still has the ability to unnerve.

  Never before had so many resources of cinema (acting, direction, spfx) been effectively deployed to manifest the darkest of dark forces.  The confrontation is not only between priests and demonic forces, viewers are also confronted and assaulted concurrently.

  Further notches up the horror by exploiting empathy (self-mutilation, a child’s physical deterioration into a corpse-like visage, a mom held hostage) and psychological fears (assault on family, home and child, religious desecration, and the thought of subjugation of our own body).

        » Brent Chastain, Top3films.com