LONDON — Today, Jewish life in Britain is under greater threat than at any time since World War II, and it is because of one man — Labour Party leader Jeremy Corbyn — and the fetid politics that surround him.

It’s now almost impossible for any British Jew to plausibly defend him. Only outliers remain.

Over the past few weeks, a barrage of reports in the British press have shed light on the Labour leader’s anti-Semitic worldview. Among the relentless slew of revelations: a video of Corbyn promoting the propaganda site of terror group Hamas in 2013, in which he took aim at his favorite subject, the perfidy of “Zionists.”

“[British Zionists] clearly have two problems,” he said. “One is they don't want to study history, and secondly, having lived in this country for a very long time, probably all their lives, they don't understand English irony either.”

“For me, Corbyn’s patronizing, racialized put-down of British ‘Zionists’ and our sense of history and English irony was no surprise” — David Krikler, Jewish communications consultant

It’s the latest link in a chain of scandals that have engulfed the Labour Party over anti-Semitism this summer. And it is serious.

Existential threat

“For a community with a history like ours, you can’t underestimate the need for Jews to feel like they belong, like they are accepted, like they are safe,” said Claudia Mendoza, head of policy at the U.K.’s Jewish Leadership Council, speaking more in sorrow than anger.

At the end of July, Britain’s three largest Jewish publications took the unprecedented step of carrying matching front pages calling Corbyn an “existential threat” to Jewish life in the U.K.

It is important to understand the gravity of what was done: The Jewish community has not felt compelled to do anything so drastic since Oliver Cromwell readmitted the Jews to this island in the mid 1600s.

Many in the community thought the papers were being hysterical. They were quickly disabused. Footage emerged of Corbyn taking part in a wreath-laying ceremony at a cemetery in Tunisia in 2014. The wreath was laid at the graves of Black September terrorists who masterminded the murder of 11 Jewish athletes at the 1972 Munich Olympics.

The photos went viral. Corbyn’s critics rushed to damn him for yet another anti-Semitism scandal, while his defenders rushed to protect him from the disgraceful smears of “Blairites” and “Zionists.” He was actually paying his respects to those killed by Israeli security service Mossad and not the Munich killers, went one line. When that defense fell apart, Corbynistas claimed he had not actually laid a wreath. Or perhaps he had but had been unaware. At this point, no one actually knew what the party line was anymore. Of course many didn’t care. And, of course, many more thought he had done nothing wrong.

When a fringe far-left magazine featured Jewish Labour MP Margaret Hodge on its cover with the strapline “The Enemy Within” emblazoned across it — a classic anti-Semitic trope that was chosen through a vote of the magazine's readership — it was yet another sign of the pollution of Britain's far left. Hodge had recently called Corbyn a “racist anti-Semite” to his face and suffered a predictable deluge of abuse as a result.

The Jewish community absorbed the escalating backlash with great alarm. Jewish organizations even demonstrated against Corbyn earlier this year. Many were angry, bitter. Now things are of a different order entirely. Now people are seriously afraid.

“The Jewish newspapers were right,” said Mendoza. “Jews from across the political and religious spectrum — literally ranging from orthodox to completely secular — have said they will not want to stay in this country under a Corbyn premiership. Who knows what would actually happen. But if that’s the case — if Jews leave en masse — how is that not an existential threat?”

Politics as usual

My social media feed is full of Jewish acquaintances and public figures talking about their fear and anger over the Labour Party. Mandy Blumenthal, a descendant of the former mayor of Birmingham, recently said in a TV interview she was moving to Israel because Corbyn had let the anti-Semitic “genie out of the bottle.”

Others are just angry.

“For me, Corbyn’s patronizing, racialized put-down of British ‘Zionists’ and our sense of history and English irony was no surprise,” said David Krikler, a Jewish communications consultant in London. “His political career has been spent in the company of Holocaust deniers, anti-Semites and terrorist groups, so I don’t need to hear him sounding like an old-fashioned anti-Semite to know exactly what he stands for.”

“It’s been interesting to see some commentators say they can no longer defend him after seeing that,” he added. “I think it’s telling that they were prepared to defend his support for organizations that literally murder Jews, whether on Israeli buses, in Olympic villages or in Argentinian community centers, but they’re more concerned by a linguistic micro-aggression. Support for anti-Semitic terror groups is fine, as long as you don’t sound like an elderly racist who’s had one drink too many in the process.”

Britain’s Jews now live in hope that the barrage of evidence that Labour is an institutionally anti-Semitic party, from its leadership to significant elements of its membership, will be off-putting to voters.

Unfortunately, for many like Krikler, that seems unlikely. The recent Corbyn revelations are not actually revelatory — his views were well-known before the issue flared up this summer. And yet they haven’t stopped him from winning two Labour leadership elections or over-performing in the 2017 general election.

Among the British Jews I’ve spoken to, the most common fear is that anti-Semitism is so niche and the scandals so abstruse that ordinary voters will find it hard to grasp what the problem is.

The unavoidable fact is that Labour is led by a politician with a lifetime history of anti-Semitic, anti-Zionist politics. Even the U.K.’s former chief rabbi, Jonathan Sacks, has called Corbyn “an anti-Semite” who has “given support to racists, terrorists and dealers of hate.” That someone of his stature should be so unequivocal in his language about the leader of Her Majesty’s official opposition is astonishing. And yet that is where we are.

“First you get the anti-Semitism, then, when you call it out, your honesty and integrity is called into question for doing so” — David Krikler, Jewish communications consultant

Corbyn and his acolytes respond as they always do. The Dear Leader has no problems with Jews, only those who support Israel. The implication being that those who label him an anti-Semite do so in the service of defending Israel.

“It is doubly isolating,” saids Krikler. “First you get the anti-Semitism, then, when you call it out, your honesty and integrity is called into question for doing so.”

Corbyn and the Jews. It’s a relationship that started out badly and now seems beyond repair, to the great distress of a people who have called Britain their home for centuries.

David Patrikarakos is a freelance journalist and author of several books, including "War in 140 Characters: How Social Media is Reshaping Conflict in the Twenty-First Century" (Basic Books, 2017).