You must walk in other men’s shoes even if they rub and pinch. The Labour politicians and political commentators who gaze with horror on the upsurge of the left should try it, then perhaps they will understand why their arguments are failing.

They are, of course, right to say that you cannot win an election unless you show you can manage the economy. It is also true that the Labour party, like failing centre-left parties across Europe, will never be in power again unless it can attract English voters, who have headed off to the right. Turning Labour into a leftwing version of the Tea Party is fatal, which is why Conservatives cannot believe their luck, and are telling their supporters to pay £3 for Labour membership and back Jeremy Corbyn.

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But sensible tactics don’t move the heart and you cannot explain why Corbyn is doing so well unless you understand the two distinct groups make up the new Labour party left.

The first are beyond saving: the political equivalent of Jehovah’s Witnesses. They dismiss all who bring uncomfortable news from the outside world as contaminated sources, who cannot be trusted. In their demonology, Labour politicians become “Tories” or “Blairites” if they contradict Corbyn. Journalists become “tabloid reporters” pursuing “McCarthyite” vendettas if they hold him to account. Their curses are the modern equivalents of “the devil and all his works”, designed to blacken the reputation of all who speak heresy the instant they open their mouths.

If you find the religious comparison far-fetched, spend a week reading the Daily Mail or Telegraph, and notice how Corbyn’s equivalents on right also fence themselves off from contrary arguments. They don’t allow one good word about the EU, BBC or trade unions to disturb the certainties of true believers. Both sides behave as if they fear their ideologies are like badly woven rugs. Let one thread come loose, tolerate one moment of doubt, and their entire political personas will unravel. Because they live in cocoons, Corbyn and Daily Mail journalists are terrible television performers.

When Channel 4 News asked Corbyn a question about his support for his “friends” in Hezbollah, he immediately lost his temper. He comes from an enclosed world where no one but the damned believes that Hezbollah are not freedom fighters but tyrannical religious reactionaries. I hear that he has cancelled a planned interview with Andrew Neil, the toughest British broadcaster, rather than endure more profane questions.

The left faithful see a clear path to the future. Max Shanly, a member of the National Committee of Young Labour, said: “The Labour left will have to act swiftly and I am afraid brutally in many cases” if Corbyn wins. MPs would “have to be brought into line”. Party workers would need to be “pointed towards the exit”. A triumphant Corbyn would purge the church of its false prophets and corrupt cardinals. A purified Labour would then go to the electorate with a genuinely socialist message. The voters would surely then renounce sin once Corbyn had offered them the way and the truth and the life.

In truth, a Corbyn victory wouldn’t lead to a coup but a shambles. The far-left Labour campaign group has only 10 MPs, which is not enough to fill a shadow cabinet. More to the point, Corbyn did not expect to win. He ran only to “give Labour party members a voice in this debate”. A Corbyn victory would be more than a disaster Labour didn’t see coming. It would be a disaster Corbyn didn’t see coming, and wouldn’t know what to do with.

The second group of left-wingers strikes me as more interesting and sympathetic. They shake their heads when their betters lecture them on the need to “move to the centre ground” and be “pro-business”. Why should we? they wonder. They have seen a devastating financial crisis pass, without the state prosecuting one of the guilty bankers. They may not understand how quantitative easing works, but they will certainly have seen government policies inflate the values of the wealthy’s assets. How extraordinary is that?

The state responds to a crisis in capitalism by rewarding the capitalists, while piling pain on everyone who was not to blame: the young, the poor, the homeless and the low paid. Perhaps readers of this article work in the public sector, and have seen the services they provide belittled and shrunk and their wages held down indefinitely. Maybe they include young readers, who can only see a future of debt and insecurity.

It’s all very well me saying that Liz Kendall deserves credit because she is the only Labour candidate to tell the party the truth about the terrible position Ed Miliband left it in. But I suspect her solution that Labour must accept a part of what the Tories have done fails to appeal to your emotions. There’s no justice in it, no sense of vindication, just the prospect of shabby compromises negotiated with disgraceful people.

Those who recoil at the thought can join a far left, which makes very few demands on them. It no longer has a Marxist programme to transform society. It goes along with anyone who opposes the status quo now – the antisemites and male supremacists of radical Islam, the criminals in the Kremlin. The loss of revolutionary self-belief may leave it intellectually bankrupt but, paradoxically, it makes it more attractive. Like Ukip or the French Front National, it just needs to say that the entire establishment is corrupt. You only have to feel that way – and we all feel that way sometimes – to agree.

The far-left’s social democratic opponents aren’t in a better position. Perhaps Andy Burnham and Yvette Cooper are mediocre candidates and better men and women would be more inspiring. But as it stands, they are like the leaders of so many of the failing social democratic parties of Europe. They are meant to be leading mass movements, but cannot attract a mass membership or win mass support at elections. They don’t know when they should compromise with the economic status quo and when they should fight.

Although all the attention is on Corbyn, this election is a greater test for his opponents. If they cannot say plainly why his plans are wrong and beliefs immoral, if they cannot challenge him and invigorate the decent people among his supporters by showing them a better way, they will deserve to lose.