Israel deserves criticism like any state, but its castigation on the Left (and elsewhere) goes way beyond that. Israel is now the world’s demonic Jew, subject to the calumnies and libels Jews have faced throughout history.

Anti-Semitism is the devil that always comes back. It never dies, it simply mutates, always adapting to the changing circumstances of the society of the day. In Europe, whether it was late antiquity, the early or high medieval period, the Renaissance, modern or post-modern, the one constant, the thread that bound these disparate times into one continuity was the oldest animosity: anti-Semitism. The feelings of resentment, envy, and hatred for the Jews of Europe have never gone away. They have a long history, and, in Britain today, that history is repeating itself.

Hatred of Jews in Britain goes back a long way, to the 13th century, with the murder of Little Hugh in Lincoln pinned on the Jewish community there, ultimately leading to the expulsion of Britain’s Jews in 1290. There have been recent rises in anti-Semitic crimes over the last few years. 2017 was the worst year on record, with 1,382 anti-Semitic incidents recorded across the UK. This was highest level recorded since 1984 when the Community Security Trust started keeping a record.

This level marked a 3% increase over the year 2016, which saw 1,346 incidents, itself a then-annual record. Alarmingly, there was no specific cause for these increases. But, as sad as it is to say, perhaps we should not be so surprised. The Center for Research on Extremism at the University of Oslo released a study in 2017 that showed that, on the whole, most of the anti-Semitism across Western Europe from 2005 to 2015 came from those of an Islamic background and — more importantly for us already here — the Left. In most countries, the political groups whom one would assume would be protecting Jews are now more likely than the far right to be persecuting them.

While Mr. Corbyn himself is not accused of anti-Semitism, he seems comfortable in the presence of those who are.

This is the case in the UK. British Jews have historically leaned left, towards the Labour Party. Now, the place you marked by the taint of anti-Semitism is the British left, more specifically the far-left of Jeremy Corbyn. All the tropes one would think of are there: accusations that the West is controlled by a shadowy group, who pull the strings of Britain’s government — or that capitalism is designed to keep the poor and workers down, controlled as it is by Jewish bankers, or that Britain’s foreign policy is dictated by the Israel lobby.

At the end of March, it came to light that Mr. Corbyn had supported the retention of a mural in East London that depicted a group of hook-nosed men playing a monopoly-type game on the backs of oppressed lower races, with an Illuminati-type pyramid in the background. Mr. Corbyn claimed that he did not know that it was anti-Semitic and that he hadn’t looked properly before. It was also revealed that Mr. Corbyn had been member of two pro-Palestine Facebook groups where anti-Semitic messages were posted.

This was only the most recent examples of Mr. Corbyn’s brushes with anti-Semitism. His closeness with tendency, which is shared by certain elements of the Labour Party goes back further. This thread on Twitter by Jack Mendel shows the extent of the rot, but some examples here will demonstrate how far it has gone.

Mr. Corbyn has repeatedly defended those who call for the destruction of the state of Israel; he has defended those who accuse Jews of the blood libel. The party has shared platforms with and suspended Holocaust deniers; he has called Hamas and Hezbollah his “friends.” He has gone nowhere near rooting out the anti-Semitism at local party levels; ex-London mayor Ken Livingstone called Hitler a Zionist and called the creation of Israel a “catastrophe.” Mr. Corbyn has repeatedly participated in Khomeinist Al-Quds marches where the Hezbollah flag has been flown and has been praised there for his stance on Israel.

The Oxford University Labour Club is rife with anti-Semitism, and Mr. Corbyn is supportive of Stephen Sizer, who claimed 9/11 was carried out by the Mossad. And finally, Mr. Corbyn has been associated with an anti-Israel and Holocaust denying group called Deir Yassin Remembered, and he was a supporter of theirs for three years after their anti-Semitism had been exposed. The group’s members included Holocaust denier Paul Eisen and anti-Semitic author Gilad Atzmon. While Mr. Corbyn himself is not accused of anti-Semitism, he seems comfortable in the presence of those who are.

Why are Corbyn and others in the Labour Party like this? The far-left has had a problem with Jews since the beginning. After all, the patron saint of hard-left thought, Karl Marx, was himself arguably anti-Jew; As Frederic Raphael says in Anti-Semitism, Marx (a grandson of a rabbi) called Jews a “huckster race” and castigated Ferdinand Lasselle for being an opportunist “Yid” for opposing socialism.

Alongside this, Jews are now also seen as an oppressive force on the world stage, a hangover from the colonial period.

As Jonah Goldberg states in his essay on Marxism in Commentary, Jews were the upholders of outmoded religious values that got in the way of the onward march of the revolution. At the same time, they were also the most fervent upholders of bourgeois values associated with the prosperous merchant and business middle-class; the secular sin of capitalism descended from the religious sin of usury that Jews were charged with during the medieval period. Jews became the avatars of capitalism, the bankers bent on thwarting the revolution and crushing the proletariat underfoot; in the end, they were the ones crushed under the boots of Soviet anti-Semitism.

Alongside this, Jews are now also seen as an oppressive force on the world stage, a hangover from the colonial period. Mr. Corbyn and those like him are invested in anti-imperialism, in joining with movements around the world, which resist the boot of western hegemony, even if this means allying with tyrannical regimes that brutalize their own populations in the name of this great resistance. Since 1967 and the Six Day War, Israel has been increasingly seen as an aggressive power, and it has lost support among Western left-wing circles. Now, it is seen as an expression of Western imperialism, a colonial project designed to deliberately disenfranchise Palestinians at best, and perpetrate apartheid and genocide at worst, leading to Israeli Jews being called today’s Nazis.

Israel deserves criticism like any state, but its castigation on the Left (and elsewhere) goes way beyond that. Israel is now the world’s demonic Jew, subject to the calumnies and libels Jews have faced through history, and acts as the lightning conductor for all the bigotries held across the political spectrum. The Left under Jeremy Corbyn is no exception. Never mind that much of the worst that Israel is accused of is specious, disingenuous or false; it serves its purpose as the focus for the far-left’s hatreds, all couched in terms of protest against “Zionism,” a euphemism that sanitizes anti-Jewish bigotry with tones of social justice activism, applied to anyone who deviates from the far-left orthodoxy.

As happened in Europe during the 20th century, increasing numbers of Britain’s Jewish community are seeing that despite their loyalty, they no longer have a political home in Mr. Corbyn’s Labour Party. The atmosphere has grown so inhospitable that there was a protest against anti-Semitism in front of Parliament organized by the Board of Jewish Deputies and Jewish Leadership Council to call out this rise in hatred. The protest itself has itself now been called a “shadowy conspiracy” against Corbyn, an attempt by “Zionists” and “British Jewry” to smear him.

Jews are now being accused of “weaponizing” anti-Semitism as part of an anti-Labour conspiracy designed to bring Mr. Corbyn down in concert with the “Zionists.” The ramping up of rhetoric from supporters of the far-Left has burst from the fringes into mainstream consciousness. While there have always been currents of anti-Semitism in wider British political and public discourse, the levels seen recently are at another level.

This rhetoric around Jews, Israel and all the rest of it, does not paint a hopeful picture for the future. What happens if Mr. Corbyn becomes prime minister? His far-left agenda is already likely to become more evident nationally if the imminent local elections go his way. If he comes to power at the head of the Labour Party in a general election, which is now not an unforeseeable outcome, then the situation, when it comes to combatting rising anti-Semitism, looks bleak indeed.