The decline of formal religion has done nothing to weaken the religious impulse. At its best, it allows Europe to welcome refugees. At its worst, it fosters a sectarianism that damns rational argument as the blasphemies of scheming heretics.

Public service broadcasters ought to study the large and often impressive academic literature on how sects manipulate and control believers. For they are under attack from three of the most potent and most cultish forces in British society: Scottish nationalism, Euroscepticism and the far-Left — or as we must now call it, Her Majesty’s Opposition.

The political faithful dream of a glorious future: a Scotland free of English tutelage, an England free of the domination of Brussels, a Britain free of greed and poverty. Like the great religious dreams of the past, these causes take over lives. But all present formidable difficulties. In political as in religious cults, believers must be insulated against doubts. The most effective method is to blacken the outside world, and make alternative sources of information appear like the Devil’s seductions that tempt the godly into darkness. As Professors Dennis Tourish and Tim Wohlforth put it in their study of political sectarianism: “There is only one truth — that espoused by the cult. Competing explanations are not merely inaccurate but degenerate”.

The initiated can never see sceptics as just foolish or misguided, let alone as reasonable people asking legitimate questions. To maintain the unity of the faithful they must be damned as malicious. The outside world is no longer a place where sensible people test their theories. It is a contaminated space, a land full of traps, set by enemies, who mean you only harm. Paranoia and hypersensitivity follow. You can see them everywhere.

Broadcasters are the natural targets. The public gets its news overwhelmingly from television and radio (which is why complaints about the power of the press are so anachronistic). They respect them because what they hear is true overall. I can say this with some assurance because the sheer tedium of following the impartiality rules drove me out of television. When you make a television documentary, you must check every fact, as you always should. But then every criticism must be put to the target of your scorn. Their answers, however evasive or dishonest, must then be broadcast. The results of this exhausting process are often bland, but I will say this for it: the documentaries are trustworthy.

Panorama made one on Jeremy Corbyn. It did not have the space to cover his endorsement of Putin’s imperial ambitions. Nor, like the rest of the mainstream media, did it emphasise the hypocrisy of a modern Left that says it believes in justice for minorities and women, then allies with the misogynists, homophobes and racists of radical Islam. Nevertheless, within his limited remit, Panorama’s John Ware asked hard questions. What did Corbyn’s supporters expect it to do when their man wants to be prime minister? They expected adulation, was the short answer. And when they did not get it, they bombarded BBC with complaints. The programme was an “establishment smear”, and a “hatchet job”. They were inside the cocoon of their cult and anything that disturbed their tranquillity had to be the result of a conspiracy of reactionary forces determined to protect the hated status quo.

A few days earlier, Bernard Jenkin, a Conservative backbencher, was lambasting the BBC for asking businessmen and women their views on whether Britain should stay in the European Union during Radio 4’s Today programme financial news round-up at 6:20. That is 6:20 in the morning. The hypersensitivity is as striking as the obsessiveness of a man who monitors the airwaves when the rest of us are asleep and finds a plot. The notion that nearly everyone involved in international trade wants Britain to stay in the single market cannot be tolerated. The fact that they come on the radio in the early morning and say so is not a fact at all, but evidence of a conspiracy against freeborn Englishmen and women.

Last year we had the Scottish National Party organising demonstrations against the BBC and demanding that it sack its political editor for asking a clumsy question at a press conference as reporters occasionally do. With Scotland already looking a little too close to a one-party state for comfort, the SNP makes no secret of its wish to get control of BBC Scotland. When and if it does, I wonder how often we will hear those difficult questions about what currency an independent Scotland will have.

Scientologists call non-believers “suppressive persons”. They are filled with harmful intentions, and must be fought without mercy. Spend too long with them, and they will have you believing that a malign force inspires anyone who speaks out of turn. Every television interviewer has noticed that Corbyn quickly cracks under questioning. He has lived in a far-left world where, whatever its divisions, no one except the corrupt, the “Zionist”, the “tool of neo-liberalism” raises the arguments a broadcaster would put to a left-wing politician as a matter of course. As he emerges blinking from the Left’s version of the Church of Scientology, he cannot accept, or even talk to, the heathens around him.

It is easy to condemn cultishness and easier still to mock, but you had better get used to it. New media technologies allow people to live in enclosed intellectual spaces, where prejudices are not only reinforced but heightened. You only read online newspapers and blogs that tell you what you want to hear. You follow an Owen Jones or a Louise Mensch on Twitter, who never once forces you to question your beliefs, or accept that your opponents are not always liars and frauds. What the American legal scholar Cass Sunstein nicely called “enclave extremism” is an observable psychological phenomenon. Put people together who share a strong view, and the differences between them vanish. Peer pressure pushes people further to the right or left; it makes their nationalism stronger, their religion more fervent. The web allows not a few hundred, in a church or at a political rally, but hundreds of thousands to convince themselves that their cult is the one true path.

The essential task for journalists and writers today is not to fight this or that ideology, but to resist the spirit of an age which proclaims that doubt is profane, and argument the ploy of a malicious conspiracy.