Exorcism is intrinsic to Christianity. From driving possessed swine into a lake to expelling a spirit from a boy who foamed at the mouth, Jesus could reasonably be considered a therapeutic exorcist. So it’s hard to tell some churches to get real and rational – although, regrettably, that message is as relevant as ever.

To claim that so many Italians have been contaminated by Satan, like some paranormal STD, is a significant aspersion

The Vatican has just set up a new exorcism training course, following an alleged increase in demonic possession. According to the Sicilian priest and exorcist Benigno Palilla, speaking on Vatican Radio, there are half a million cases reported in Italy yearly, and demand for assistance has tripled. To claim that such a large number of Italians have been inadvertently contaminated by Satan, like some paranormal STD, is a significant aspersion on a nation of 60 million people. Palilla lays the blame on people who visit fortune-tellers and tarot-readers. These practices “open the door to the devil and to possession”.

A quick breeze around the Catholic Herald website certainly confirms that exorcism is a live topic. And in 2014, the Vatican officially recognised the International Association of Exorcists.

So what’s the problem? The first is that people get hurt. Really hurt. Recent UK government statistics suggest that almost 1,500 child-abuse cases a year are linked to notions of witchcraft and demonic possession. The Metropolitan police’s Project Violet was set up to explore child abuse connected to spiritual beliefs. I have written about Nigeria’s “witch children”. And there was the recent horrific case in Nicaragua of Vilma Trujillo, who died after being burned alive. This all demonstrates that the danger is neither localised nor irrelevantly ancient.

Second, those diagnosed as “demoniacs” often get spiritual rather than medical attention. The 2015 case of a GP struck off for taking a mental health patient to church for an exorcism is probably unusual in this country. But it should go without saying that distressed people benefit more from an evidence-based intervention than a belief that the Dark One is tormenting them.

Schizophrenia and bipolar disorder are the traditional candidates for a false diagnosis of demonic infestation. The Catholic church includes psychiatric experts on its exorcism panels for balance and information. But there are other confusing conditions. Mental health charities estimate that between 5% and 28% of the adult population hear voices, and that most are not mentally unwell. Sleep paralysis is another common experience that can alarm those who don’t know about it. In both cases, the subject will probably be absolutely fine on finding out that they are neither at the beginning of a personal disintegration nor the target of demons. Superstition is simply not the most constructive therapy.

But another thing bothers me: the class of specialists produced by exorcism courses and professional bodies. These specialists derive status from the practice of their “skills”, in the manner of Maslow’s hammer: when you have a hammer, everything starts to look like a nail. An investment in the intellectual models of demonic possession and exorcism can bring catastrophic momentum.

A quick look at history demonstrates how just one educated yet gullible fool can wreak havoc: in the witch-hunts of Labourd, in France, in 1609, Pierre de Lancre brought at least 70 people to the stake. There are many more career witch-hunters of whom similar stories can be told.

The burning of an Anabaptist by the Inquisition in 1571, in an engraving by Jan Luyken. Photograph: UIG via Getty Images

Even more worrying is the creation of a whole institution – in which case the momentum becomes harder to stop. The Inquisition started as a body to root out heresy, but soon became a witch-hunting machine with a specialist workforce – the Dominican order – subject only to the pope. It created human misery on a grand scale before it was stopped from burning witches.

I detect some ambivalence within the church itself about possession and exorcism. It must function as a political body that accommodates a very wide range of views. That doesn’t mean that every clergyman or bishop agrees with all of them.

The formal Vatican decree that approved the International Association of Exorcists recognised it as an organisation of Catholics, not operating in the name of the church, but having some accountability to the Vatican. This would be one way – in the event you couldn’t make the exorcists go away – of maintaining some form of discipline over them. I hope I’m right in that interpretation.These days the most egregious cases of abuse associated with exorcism are from evangelical churches. This may be because that kind of religiosity appeals to the most isolated, marginalised, often disadvantaged and inward-looking communities.

So how do we balance freedom of speech and belief against the potential for harm? I would focus on professional exorcists and their fees. The Consumer Protection from Unfair Trading Regulations cover psychic services, but not exorcism. Where exorcism is charged for, it should be against the law. You shouldn’t charge for fairy dust, and you shouldn’t charge to expel demons.

This wouldn’t affect Catholic services, but it could be used against independent, evangelical “pastors”. (This is where “respectable” religion gets off lightly compared with “frivolous” superstition.) To stop the belief proliferating, you have to denature the specialists.

• Deborah Hyde is editor of the Skeptic magazine