The reaction wasn't completely predictable, however. Billy Graham called it satanic, but the Tunisian government banned The Exorcist, condemning it as "unjustified propaganda in favour of Christianity". The Catholic News praised its deep spirituality and Catholic churches reported a huge increase in those taking confession.
Even today, The Exorcist, still to win a home video release, provokes a strong reaction among people - whether they've seen it or not.
...but then again, what does Claire Rayner think?
"I'VE SEEN it loads of times. The opening image in the desert sticks in my mind. I don't know whether it was the director's intention, but the archaeologists are very cliched and the colonial workers very exploited. When it moves to America and the demonic possession, it's like the colonial oppressor gets his comeuppance.
"I see it as a comedy. Cinema's a social situation and I don't know how scared you can be in that situation. Maybe I'm just too rational."
Stewart Home, author
"WHEN I was 11, I saw the trailer at the cinema. In it, a car pulls up outside a house on a foggy night. The voiceover says: 'Something almost beyond comprehension is happening to a girl on this street, in this house.' A guy gets out of the car and walks under a streetlight, looking up at the house with light blazing out of a window. The image is based on Magritte's Empire of Light. You know this man is a last resort and yet he appears to be a dark, shadowy presence threatening the house. It's clearly the scariest film ever made. But it's also the best."
Mark Kermode, film critic and author of 'The Exorcist', a study of the film (BFI Modern Classics)
"I'VE NEVER seen it and it sounds like a load of rubbish. It's about demonic possession, isn't it? I don't believe in any sort of supreme being so I wouldn't want to see a film about the devil. I'm a grown-up lady and I want to see a film that says something to me. Anything that's real frightens me silly. Apocalypse Now was terrifying: it was true."
Claire Rayner, agony aunt
"I'VE A very old fashioned view of the devil - horns, flicking red tongue etc - and the film tampered with that image. I found the whole vomit, revolving head and rolling eyes stuff overblown - a technicolour approach to religion. It was gruesome and awful, but it didn't convince me. The Jesuit priest I found more convincing.
Cristina Odone, former editor of 'The Catholic Herald'
"I NEVER watch cult films like that. I'm not into exorcism for a start. It sounds like an unpleasant film and I want to be entertained in the cinema. The Birds is a scary film. But I don't go to the cinema to be scared - I can do that in the newsroom."
Jon Snow, newsreader