The British political crisis deepens. This is not a Brexit matter, though that is critical enough. Rather it concerns Jeremy Corbyn, leader of the opposition Labour Party – which is now, according to a poll last month, four points ahead of the ruling Conservative Party. Though Corbyn isn’t personally popular, he could become – on this showing will become – the next British prime minister.

Yet it becomes increasingly obvious that Corbyn, 69, has for all his political life until being elected to lead the Labour Party in 2015, allied himself with those who wish to destroy the state of Israel. Last week, the Daily Mail published photographs taken in a Tunis graveyard in 2014, a year before he became leader, showing him bearing a wreath near graves of the Black September terrorists who killed 11 Israeli athletes and a German policeman at the Munich Olympics in 1972.

Corbyn, in a testy TV interview, said he was honouring others killed in an Israeli airstrike, whose graves were some distance from the Black September graves before which he was standing, and that there were many people holding many wreaths. It’s hard to take that seriously.

But we should take Corbyn seriously. Only by doing so can the beliefs he holds – on Zionism, on Israel, on Palestine – be understood. For his is only partly anti-Semitism of the traditional kind, whether based on religious hatreds, or stereotypes of Jews as greedy capitalists intent on crushing honest workers.

His critics think he is destroying trust in the party – and not just among Jews. His own deputy leader, Tom Watson, warns that Labour will “disappear into a vortex of eternal shame and embarrassment.” A prominent Labour member of parliament and former minister, Margaret Hodge – who is Jewish, and lost relatives in the Holocaust – publicly called Corbyn an anti-Semite. Threatened with an investigation, she retorted that she would take legal action against the party; the threat was dropped.

Corbyn has repeatedly said that he wants to drive anti-Semitism from his party, but he has much anti-Semitic-seeming form to deny. In 2009, he referred to representatives of Hamas and Hezbollah as “friends” at a meeting in Parliament. In 2010, he took part in an event on Holocaust Memorial Day in which a Palestinian activist, Haidar Eid, claimed that Israelis had been “Nazified.” And so on.

He and his supporters on the party’s National Executive Committee have so far refused to have Labour fully commit to adopt the International Holocaust Remembrance Alliance guidelines on the definition of anti-Semitism. They have insisted on excising four concrete examples of what speech would be deemed anti-Semitic. In the most fraught example, they have not included the guidelines’ examples which define as anti-Semitic any claim that “the existence of the state of Israel is a racist endeavour,” or comparing contemporary Israeli policy to that of the Nazis.

A compromise may be reached before the Labour Party’s conference in late September – though it’s also reported that Corbyn wants to add a clause stressing that criticism of Israel is legitimate – as, indeed, the Alliance guidelines already state.

It may move the dispute off the news bulletins and the front pages. But it will not change Corbyn, or his supporters. They believe in something higher than mere workaday dislike of Jews. They believe that Zionism, the belief in Israel’s creation and existence, should be defeated – which can only mean that Israel itself should cease to exist – as Hamas calls for in its charter. That charter was updated last year with a section recognising for the first time the 1967 border between Israel and the Palestinian territories, an apparent implicit recognition of Israel. But it goes on to say that the struggle against “the Zionist enemy” continues, and that there is no “alternative to the full and complete liberation of Palestine, from the river to the sea.”

The Hamas leader, Khaled Meshaal, added an important rider at the press conference introducing the charter: “Hamas affirms that its conflict is with the Zionist project, not with the Jews because of their religion.”

The rider is important to the group, because it puts them on side with Western far leftists who like to make the same distinction. The latter have, for decades, seen the world through an anti-imperialist lens, influenced, as Jamie Palmer writes in a recent essay, by such works as Frantz Fanon’s “The Wretched of the Earth” and Edward Said’s later “Orientalism,” both of which stress Western guilt and Israel’s position as an outpost of imperialism. This produced, writes Palmer, “the uncritical valorisation of any indigenous movement that positioned itself as hostile to Western aims and interests.”

Corbyn and the group around him grew up with these attitudes. They could believe in the goodness of their motives, because they were on the side of the “wretched of the earth” and against those whose relative wealth both in Israel and in the diaspora made them obvious oppressors. They could, in all sincerity, deny anti-Semitism – some of their friends were Jewish, for heaven’s sake! – but they were against the Zionists. And if their friends thought the Zionists must be killed, well, they wouldn’t say that themselves but that was their friends’ right, and they would – literally – stand with them.

Corbyn, though he has twisted this way and that to avoid taking responsibility for his past positions – or even admitting he had them – may not suffer electorally because of his views on Israel. He does not appear to be suffering now. And he may even gain on this issue. Hundreds of British academics, musicians and artists are promoting a boycott of the country. For the majority, it doesn’t seem to be of great importance.

It isn’t that those who may put him in 10 Downing Street are anti-Semitic. They’re just not all that worried if Israel exists. Or not.

John Lloydco-founded the Reuters Institute for the Study of Journalism at the University of Oxford, where he is senior research fellow.