The Jewish community leadership has been pleading with the Labour Party to deal properly with antisemitism and become again the party of moral decency.

Surely no-one in the Jewish leadership believes this will happen? Even if the party adopts the full International Holocaust Remembrance Alliance definition, does anyone really think its antisemitism will then go away?

The core problem goes way beyond Labour. It is that the new antisemitism, expressed through virulent anti-Israelism, is now the defining motif for “progressive” circles.

This attitude intrinsically repudiates the unique right of the Jews to self-determination in the land which was only ever the national kingdom of the Jews — a right which is not just the basis of Zionism but Judaism itself.

It is a campaign of demonisation and delegitimisation applied to no other people. It is based on systemic falsehoods and distortions, obsessional malice and deranged conspiracy theory. It blames Israel for crimes of which it is not only innocent but is the victim. It defames it as a unique agent of global harm. These are the characteristics of antisemitism through the ages.

The progressive world attacks Israel because its signature cause is Palestinianism. That in turn is based on destroying Israel and repudiating Judaism. You can see this from the supposedly moderate Palestinian Authority: from what its leaders actually say, from its maps and insignia which show the whole of Israel as “Palestine”, and from its educational materials and media which incite the destruction of Israel and the murder of Jews.

Led by Mahmoud Abbas who boasts a doctorate in Holocaust denial, the “Palestinians” base their fictional identity on writing the Jews out of their own national story in the land.

They pump out an unstoppable torrent of antisemitism — demented conspiracy theories about Jewish bankers controlling the world, Jews subverting American foreign policy, Israelis as wanton child-killers.

So why should anyone be surprised when their British cheerleaders in the Labour Party and beyond reproduce exactly the same disgusting tropes? How, indeed, can anyone claim to be against antisemitism if they support Palestinianism at all?

Tragically, this progressive animus against Israel has poisoned the minds of too many British Jews as well. Not just the kind who say Kaddish for Hamas terrorists or provide cover for Jeremy Corbyn by promoting their own pathological hatred of Israel.

There are other Jews who circulate the same venomous lies and distortions about Israel but who say they support its right to exist (well, thanks) or even call themselves Zionists.

Worse yet, however, is Britain’s Jewish leadership. It refuses to call out Palestinianism for its intrinsic antisemitism and to hold up its supporters for deserved obloquy in the public square. Instead — astoundingly — it bashes Israel with the ignorance and distortions of its enemies.

Thus the Board of Deputies Senior Vice President Sheila Gewolb denounced Israel’s new nationality law for its “regressive steps”. She didn’t clarify; but presumably she was channelling the Israeli and British left who storm that the new law is “racist” , turning Israel’s minorities into second-class citizens.

But this is totally untrue. Minorities will continue to have equal rights as Israeli citizens. The only thing reserved to Israeli Jews alone is, as always, the right to national self-determination. If they didn’t have this right, Israel wouldn’t be a Jewish state at all.

“Being Jewish is a wonderful thing, but this should not lead to doing down others,” said Gewolb. That is jaw-dropping. Israel isn’t “doing down” anyone. There’s nothing wrong with having one national Jewish flag, one official language which is Hebrew and one set of national holidays which are Jewish. That’s because Israel is a Jewish nation state. Does Gewolb have a problem with that? Or is she merely ignorant of what a nation state actually is?

Worse still, she said: “The lesson of Jewish history is that societies are stronger when minorities are affirmed, and they decay when minorities are degraded”. What? Was she really suggesting that Israel’s behaviour is akin to that of the Nazis? Isn’t this precisely the kind of antisemitic insult of which Labour members stand accused?

So the Board of Deputies is not only failing to call out the wellspring of anti-Jewish bigotry. It is promulgating some of the very falsehoods that incite people to hate Israel and the Jews – while simultaneously shouting about Labour party antisemitism.

Has there ever been a community less suited to an existential battle than this one?

Melanie Phillips is a Times columnist