There is an organization in the UK called the Christian Medical Fellowship. OK, no problem, you might think — nothing wrong with Christian fellowship, nothing wrong with doctors who go to church or pray together. But you’d be wrong. Religion poisons everything. This is what the 4000 members of that organization talk about: demons.

The New Testament tells us that Jesus has commissioned us to ‘drive out demons’ (Mk 16:17), and we must be ready to respond to this commission if and when we are called to do so.

Psychiatry, then, is not the only domain within which we need to be aware of demonic influence, and perhaps it is not even the most important such domain. Furthermore, we cannot expect to make a simple differential diagnosis according to certain signs or symptoms of demonisation. However, this does not exclude the need to consider other possible links between demonic activity and mental illness.

Demon possession and mental illness, then, are not simply alternative diagnoses to be offered when a person presents with deliberate self harm or violent behaviour, although they may need to be distinguished in such circumstances, whether by spiritual discernment or the application of basic psychiatric knowledge. It would seem reasonable to argue that demon possession may be an aetiological factor in some cases of mental illness, but it may also be an aetiological factor in some non-psychiatric conditions, and in other cases it may be encountered in the absence of psychiatric or medical disorder.

How about some truth in advertising: I suggest they change their name to Christian Witch-Doctor Fellowship. I would not want to go to a doctor to discover that he would diagnose depression as possession, or that an ulcer was demonic.

Unfortunately, the US has its own national quack, Dr Oz. The New Yorker has an excellent exposé of Oz.

“I want to stress that Mehmet is a fine surgeon,” Rose said, as he did more than once during our conversation. “He is intellectually unbelievably gifted. But I think if there is any criticism you can apply to some of the stuff he talks about it is that there is no hierarchy of evidence. There rarely is with the alternatives. They have acquired a market, and that drives so much. At times, I think Mehmet does feed into that.”

At times? The man uses his bully pulpit to endorse destructive quacks, and peddles snake oil himself. I don’t care if he is a fine cardiac surgeon; he operates, presumably with high competence, on one patient a week, and then misleads millions.

There are many legitimate and articulate opponents of genetically modified products and, for that matter, of conventional medicine itself. But Oz has consistently chosen guests with dubious authority to argue those positions. Joseph Mercola, an osteopath, runs mercola.com, one of the most popular alternative-health Web sites in the country. Oz has described Mercola as a “pioneer in holistic treatments,” and as a man “your doctor doesn’t want you to listen to.” This is undoubtedly true, since Mercola has promoted such alleged experts as Tullio Simoncini, who claims that cancer is a fungus that can be cured with baking soda. Mercola has long argued that vaccines are dangerous and that they even cause AIDS. When Oz says that Mercola is “challenging everything you think you know about traditional medicine and prescription drugs,” it’s hard to argue. “I’m usually earnestly honest and modest about what I think we’ve accomplished,” Oz told me when we discussed his choice of guests. “If I don’t have Mercola on my show, I have thrown away the biggest opportunity that I have been given.”

It’s bizarre. He thinks his position within the bona fide medical profession means he now has a responsibility to open the door to frauds. It makes no sense…until you discover that the man doesn’t have the slightest understanding of science.

I was still puzzled. “Either data works or it doesn’t,” I said. “Science is supposed to answer, or at least address, those questions. Surely you don’t think that all information is created equal?”

Oz sighed. “Medicine is a very religious experience,” he said. “I have my religion and you have yours. It becomes difficult for us to agree on what we think works, since so much of it is in the eye of the beholder. Data is rarely clean.” All facts come with a point of view. But his spin on it—that one can simply choose those which make sense, rather than data that happen to be true—was chilling. “You find the arguments that support your data,” he said, “and it’s my fact versus your fact.”

Millions worship this guy, and watch his show religiously for medical advice. But his story is to simply throw away evidence-based reasoning.

I told Oz that I was aware of no evidence showing that Reiki works. He cut in: “Neither am I, if you are talking purely about data. But this is one of the fundamental disconnects between Western medicine and what people often refer to as complementary medicine. Not everything adds up. It’s about making people more comfortable. I offer things like massage therapy, and offered Reiki if people wanted it. I did not recommend it, but I let people know it was their choice.”

Please. Give me medical treatments that are backed up by data, rather than ones that make Dr Oz feel good.