Another classic of American horror, I know. I don't think I ever saw it all the way through until the theatrical release of "The Version You've Never Seen"- which in my case was literal.
The Exorcist, for those who don't know, is about a little girl named Regan who gets possessed by a demonic entity. After scientists fail to find a problem with her, a young priest in the midst of his own crisis of faith and an older priest who has dealt with the demon before must team up to save the little girl. The story is fairly straight forward but the horror comes from little touches.
In the "Version I had Never Seen" or whatever, they superimposed demonic faces in negative spaces on screen before the possession to show the coming of the evil. Like the subliminal Brad Pitts showing up in Fight Club, the demonic stalking of the mother and daughter made some good scares downright disturbing. Besides the subliminal faces, there is plenty in plain sight to freak you out. The dinner party scene where little Regan tells an astronaut, "You're going to die up there" is freaky. Seeing the poor girl get a spinal tap for no reason is horrific. And once the demon shows up, the girl starts doing and saying the most perverse things to shake the faith of the exorcists.
Sure, there is lots of green pea soup vomit, but it looks pretty fake. Worse is when it is dried and crusted on the people in the room. Besides bodily fluids like pee and blood, there is not a lot of gore in the movie. One scene with a crucifix being used in a rough manner is kind of hard to watch. But really, this is a movie of unsettling actions and disturbing words coming from the face of innocence.
Expertly directed and filled with good scares, this is a classic for a reason.