‘On December 26 1973, a movie called The Exorcist opened in theatres across the country and since then all Hell has broken loose.’

That was the reaction of Newsweek a few weeks after the film was released and when audiences were still queuing for hour after hour, block after block, to get seats. Some cinemas were showing it on 24-hour cycles, with an hour break between each showing to give staff the time to clear blocked toilets and wash away the vomit in the aisles and on the seats. Some stopped selling sweets, popcorn and soft drinks.

Looking back to a time when faith and worship played a huge part in American life – and politics – it seems extraordinary that a film about demonic possession would be released on Boxing Day, the second day of Christmas. The original intention had been to have it in cinemas around Halloween, or just before Thanksgiving, but pre-production problems meant delays. Warner Bros studio was, for obvious reasons, worried about placing it in the Christmas schedules, but was won over by the argument that the holiday season meant greater audience potential for a film they already feared might struggle to find an audience at any time of the year.

It was that fear of box office failure which also led to the decision not to go ahead with press previews. Critical reception – often fuelled by huge marketing efforts by the studio and by PR companies for key cast members – could still make or break films at a time when newspaper/magazine sales were huge; and the general view of the studio was that The Exorcist was going to be a hard enough sell without it being kicked around by power-wielding critics, negative editorials and commissioned opinion pieces from leading Church figures.

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Biggest box office Christmas release in history

Again, it was a wise decision. By the time the critical reaction kicked in, the film had become a huge word-of-mouth success. Within weeks it had become the biggest box office Christmas release in history, a title it was to hold until Titanic was released in 1997. It still ranks at number two.

So, it didn’t matter that the hugely influential evangelist Billy Graham argued that evil permeated the film and that the reels were, themselves, possessed. It didn’t matter that Church groups picketed the film for most of the 105 weeks of its initial run. It didn’t matter that political organisations, particularly in rural areas and some southern states, tried to get it banned. It was as if the audiences themselves were already possessed.

New type of horror film

The Exorcist introduced a new type of horror to cinema: a type that emptied bowels and stomachs across America and later the world. Horror was nothing new, of course. It had been there from the very invention of filmmaking and for a glorious period in the 1930s – when Universal paraded Frankenstein, Dracula, the Wolfman et al – it was one of the most popular and profitable genres.

But it was horror still underpinned with fantasy. However much it may have made you clutch the armrest or the hand of the person beside you, you always knew that it was make-believe. You could see behind the special effects and make-up. You could see behind the curtain and the cleverly contrived make-you-jump moments. Half the fun of the traditional horror film – as it was with the stories of Poe and Grimm – was waiting for the scare and then laughing as you recovered or pretended not to be scared at all. Then you walked home and went to bed without any sense of unease.

You didn’t know when the jump moment was coming. You were seeing things you had never before seen in a film. This was the devil in action

The Exorcist changed all that. You didn’t know when the jump moment was coming. You were seeing things you had never before seen in a film. Even the gorier horror of the late 1960s and the devilish thrills of Rosemary’s Baby didn’t prepare you for The Exorcist. This was the devil in action. Maybe even in the seat beside you. Or that unexpected shadow on the wall when you walked home. That relentless sense that what you were seeing was as close to real terror as you had ever experienced: a terror which made huge numbers of viewers leave their hall and bedroom lights on for weeks or months after they had seen it.

And at the centre of that terror was a 12-year-old girl called Regan (played by the unknown Linda Blair) who messed around with the sort of toy store Ouija board which could be found in millions of homes. More than that, the film was based on a book which author Peter Blatty had built around dozens of cases of verified ‘possessions’ (although whether it was through mental disorder or diabolical invasion was left open to question).

The film version went deeper, though. This wasn’t just a story that would unsettle those whose Christian/biblical faith led them to believe that the devil was a real, everyday threat: a real, persistent, determined-to-win enemy of God. This was a story which also unsettled those of us who, while atheist or agnostic, still acknowledged that there was a very specific force which could be understood as evil. What we saw on the screen looked and sounded like evil.

So uncomfortable was I when I first saw it, in March 1974 in London, that there were a couple of moments when I was ready to leave – which quite a few people already had. I’ve watched it a few times since then and I’ve always felt the same sense of discomfort, even though I could take you through exactly how each scene was set up and shot. That’s why it works. It’s why the best films in any genre work. You know how it’s done. You know how every last detail is linked together from script to final take, yet you believe. Truly believe.

Concern of senior Church figures

Roger Ebert – a superb film critic – noted at the time: “I am not sure exactly what reasons people will have for seeing this movie; surely enjoyment won’t be one. Are people so numb they need movies of this intensity in order to feel anything at all?” It was a very good point. One which puzzled and still puzzles critics, psychiatrists and theologians.

Why would you want to be scared to the point of terror, trauma and sleepless nights? A paper published by the Journal of Nervous and Mental Disease in 1975 documented a number of cases of ‘cinematic neurosis’ triggered by the film. Journalists were also worried that the film was actually distracting attention from the ongoing Watergate scandal, while senior figures in Catholic and Protestant churches expressed concern that the film would encourage “a very dangerous belief in both the occult and Satanism”.

Fifty years on and The Exorcist holds on to its claim as probably the best ever horror film; one which still has the impact on a first-time viewer that it would have had in 1973 (just look at how many horror films have their rating certificate reduced within a decade or so). But it does have a worrying legacy, I think. In breaking down the boundaries it paved the way for two new generations of horror films whose only purpose is to disturb. There are no boundaries and few moments of redemption in them. Maybe the devil did win after all.