To say that the Labour party is in crisis because it is ‘too left-wing’ is to miss the point spectacularly. With eyes wide open, and all democratic procedures punctiliously observed, its members have chosen in their tens of thousands to endorse not ‘the left’, but an ugly simulacrum of left-wing politics.

They have gone along with the type of left-winger who flourished in the long boom between the fall of the Berlin Wall and the great recession. The hypocrite who damns oppression, but only if it is committed by western countries. The pseudo-egalitarian who will condemn sexism and homophobia, but not the prejudices of favoured regimes and minorities. The fake anti-racist who will attack the ‘far right’ while echoing the fascist conspiracy theory.

Let us see how their ‘new politics’ are progressing. At the time of going to press, and we accept that this is a provisional tally, Labour has had to suspend Ken Livingstone for invoking Adolf Hitler in the latest of his many attempts to bait and humiliate Jews. Also suspended is Naz Shah, one of its two Bradford MPs, for saying that Israelis should be transported to America. Hanging alongside them on Labour’s drooping dirty-laundry line are a good half-dozen Muslim Labour councillors, suspended for saying that Jews were really behind Islamic State, or for echoing Shah’s call for the ethnic cleansing of Israeli Jews, or for telling Israeli footballers that their country was the new Third Reich.

Cynics dismiss the fuss. There are 2.7 million Muslims and only 260,000 Jews in Britain. If left-wingers alienate Jews, the profit-and-loss account is still in the black, particularly when a large segment of the white bourgeois left is as keen on laying into ‘the Zionists’, as they so daintily call them. It is not true to say all British Muslims want fevered rhetoric against Jews (any more than it is to say that all Jews oppose Corbyn). But in areas with large Muslim minorities, even the Liberal Democrats have played the race card. If Labour doesn’t join them, it will be beaten by them. That’s the ‘new politics’ and we had better get used to it.

In any case, they continue, Labour is more like Ukip than the BNP. It doesn’t defend its Livingstones and Shahs but suspends them, while ducking questions from reporters who wonder why they were attracted to Labour in the first place.

To me, there is every reason to make a fuss. Labour’s Jewish question is a symptom of a wider sickness in the party, which will discredit both it and left-wing culture if left unchecked. That culture’s huge and not wholly unwarranted advantage relies on the assumption that leftists are good people. The left did not invade Iraq, it did not crash the banking system, it did not impose the bedroom tax, or ransack company pension schemes and head off to Monaco. Even when the left was wrong, it was in the 1066 and All That formulation ‘wrong but wromantic’. The Tories, even in their fleeting moments of competence, which occur ever more rarely these days, could only ever be ‘right but repulsive’.

‘The left’ can get away with the assumption of romantic virtue because it has been on the sidelines. Who cared what it did or said? Now Corbyn leads the opposition and all its failings are on display.

The ‘left’, you might have thought, is against the far right. ‘Racist’ and ‘fascist’ are the insults leftists throw against everyone from their stuffy parents to members of the parliamentary Conservative party. Yet it is normal now to hear the fascist conspiracy theory fall from the lips of a supporter of Jeremy Corbyn or a supporter of Marine Le Pen.

Supporters? What am I saying? Corbyn himself is happy to endorse the most disgraceful liars. Corbyn decided that an Arab deported for saying that Jews feasted on the blood of Christian children was a victim of the ‘pro-Israel lobby’. He opined that the church was doing the Zionists’ dirty work when it disciplined an Anglican vicar, from Haslemere of all places, who cited Holocaust deniers and said 9/11 was the fault of the…oh go on, guess. Polite political commentators say that I must add at this point that ‘Jeremy Corbyn is not an anti-Semite’. Sorry to be a fact-checking bore, but if he isn’t a racist, then he is a remarkably stupid old man who in George Orwell’s phrase is ‘playing with fire without knowing fire is hot’.

If Labour is ever to win again, the poison from the far left will have to drained. And not just because Corbyn will keep the right in power indefinitely. Nothing will truly change unless there is a change of mind as well as a change of tactics. Those capable of self-criticism should at least consider that the prejudices they have endorsed may have been immoral. They should, but probably won’t. I can guess their reply. They will say: ‘We have not endorsed racism, we have just engaged in legitimate opposition to Israel.’

I could go on about how the supposed supporters of the Palestinians on the left do not appear to understand that Jeremy Corbyn’s ‘friends’ in Hamas and Hezbollah oppress Arabs as much as Jews. I could add that a left that cannot oppose clerical tyrants is no longer a force for progress in the world. But let us move away from the blood- and God-soaked ‘Holy Land’, and consider how, as a matter of course, the faction of the left in charge of the Labour party appears on the propaganda channels of Iran and Russia, and how it sides with Islamist conservatives against Muslim liberals.

The political consequence of these shameful double standards will be enormous. Not only is the Corbyn left comfortable with regimes that all decent liberals and leftists have a duty to oppose. It is comfortable with regimes that mean Britain harm. Patriotism may be an embarrassing subject today and no one talks of ‘traitors aiding the enemy’, but this does not mean that the patriotic impulse has died. The British public will still notice that the leaders of the opposition are more comfortable with hostile foreign countries than their own country, and the majority of their own countrymen and women too.

In France it is automatic for respectable politicians to condemn racism and then add ‘and anti-Semitism’. Perhaps anti-Semitism is not taken as seriously here because the Nazis stopped at the Channel and we never had to live through our own version of Vichy. But there is a more contemporary reason for the failure to tackle it, or even admit its existence, that could unravel social-democratic politics.

Most Jews are white. And across the middle-class left, it is held that racism is not racism when it is directed against whites in general and that entitled aristocrat of our age, the straight white male, in particular. The dangers for centre-left parties should be obvious. In Europe and in Donald Trump’s America, the white-working-class base of social-democratic parties is falling away. Voters will carry on leaving if they keep hearing expensively educated voices tell them in perfectly constructed sentences that they are the oppressors who must be overthrown. Why should a white man with miserable job and no prospects tolerate a left-wing elite that casts him as an overprivileged villain? If I were in his shoes, I would loathe the lies and point-scoring and want nothing to do with such politicians.

A ‘left-wing’ egalitarianism that takes so little notice of class is fake. Like a ‘left-wing’ foreign policy that is on the side of the reactionary and obscurantist, it will first infuriate and then fail.

The tragedy for Britain is that a dose of true left-wing radicalism is needed now. Only the most complacent Tories maintain that our economic order should continue unreformed. Simon Wren-Lewis, Chris Dillow and other left-wing economists whom I have always respected say there is a good case for many of John McDonnell’s economic policies. An entrepreneurial state that supports start-ups through a government investment bank is a sensible way of dealing with the manifold failings of the banking system to promote new business. Left-wing warnings against the government’s combination of austerity with close-to-zero interest rates are wholly justified. When the next shock comes, the supposedly prudent Osborne will have left this country naked before the storm without one monetary lever to pull.

Like a case of dysentery, the Corbyn moment will pass. My fear is that it will be replaced not with a serious commitment to reform, but with the terrified conformism that characterised the Labour party after Tony Blair became leader. Labour will be so desperate to prove it is strong on national security that it will agree with whatever the generals and security services propose. It will be so desperate to appear economically reputable that it will endorse rather than oppose the stagnant system the Cameron government has presided over.

The most haunting line about politics I know comes from the Italian communist Antonio Gramsci. While he lay in one of Mussolini’s jails, he wrote ‘The old is dying and the new cannot be born; in this interregnum a great variety of morbid symptoms appear.’

Corbynism is a morbid symptom — the curse my generation of left-wingers have handed to on to our children, who deserved a better and more principled politics. In all likelihood, when the interregnum is over, we will return to normality, even though normality is the last thing Britain needs.