Garvan Walshe is a former National and International Security Policy Adviser to the Conservative Party.  He runs Brexit Analytics.

In Gothenburg, on Saturday, the mob gathered outside a synagogue and pelted it with molotov cocktails. Children were ushered into the basement for their own protection. Police were on the back foot: their intelligence should have detected the plans. As swift as the police were slow, the far right chose to blame it on Sweden’s social model. The conflict between its social model and Muslim immigration has become a theme of theirs. Nigel Farage recently misinterpreted statistics to describe Sweden as “the rape capital of the world” (it in fact has a broader definition of rape, and makes it easier for women to report the crime). Should he be in any doubt, he could always pop down to the Ecuadorian embassy and ask his mate there, who denies allegations that he added to the statistics.

The claim here is that Sweden’s immigration policy somehow makes it a soft touch for Islamist movements. So best to close the borders. Discount for a moment that closing the borders is the far right’s solution to every problem.

What is going on in Sweden is another phase of the long-running conflict between political Islam, western liberalism and its domestic enemies. It happened here as early as 1988, when Salman Rushdie’s Satanic Verses was publicly burned. In the Netherlands, where Theo Van Gogh was murdered. In Denmark, over the cartoons of Mohammed. And in countless places because of terrorist attacks, demands for censorship and other legal exceptions made by groups claiming to represent Muslim communities in the West.

It’s a conflict with four sides, only three of which show any desire to fight. Islamists themselves oppose the West because of what they consider to be its godless liberalism. They often deny there’s such a thing as Islamism. All Islam, they say, – unwittingly channelling Skunk Anansie – is political. At their most sophisticated (the disgraced Oxford academic Tariq Ramadan) they argue that Muslims living in Western countries should be able to run their lives according to Islamic traditions and law. It sounds reasonable – but for traditional Muslim views of women’s rights, blasphemy, and homosexuality, and modern Islamism’s attitude to the Jews.

Liberal westerners feel trapped. They see religion at most as a matter of conscience, and want to treat Muslims equally to everyone else – but don’t want to face the quandary of how to deal with a religious minority, significant numbers of which oppose social equality in principle, but at the same time are victims of racism and prejudice.

It is racism and prejudice that a new breed of pseudo-liberal Westerners is happy to exploit. They elide the distinction between Islam and Islamism, present themselves as outsiders fighting the liberal establishment (if they took musical inspiration, it might well be from The Cure) and win the support of ex-liberals dismayed by liberal pusillanimity.

That leaves the Far Left, who think that identifying with the “oppressed group” is more important than preserving values they otherwise pretend to profess. Their attitude is one of cultural marxism (before that phrase was appropriated by the alt-right), best expressed in the slogan The Prophet and the Proletariat, the title of a Marxist tract (and still occasionally daubed on the walls at SOAS). Their enemy is the United States, and they find Ayatollah Khomeini’s conclusion that if the US was the Great Satan, Israel must be the Little Satan, congenial. It’s a small step from this to claims that Jews should do more to speak out against Israeli policies that the Left disagrees with, and a smaller step to arguing they share responsibility for Israel’s actions. Though no mayor of a major Swedish city has gone as far as to say that the Zionist movement had the support of Hitler “before he went mad”, the Jewish community in Sweden is becoming increasingly concerned about anti-semitism growing on the Swedish left as well.

This combination – Islamist radicals pretending that all Muslims share their political agenda and it should be granted to them as a matter of religious tolerance; anti-immigrant populists taking this as a reason to fan anti-Muslim hatred; and the Far-Left’s insistence that my enemy’s enemy is my friend – has enabled the return of anti-semitism to Sweden, as it has returned elsewhere.

Politicised Islam presents a serious challenge to the liberal institutions that have evolved in Western Europe over the last centuries. Anti-muslim bigotry compounds it. Those trapped Western liberals need to defend the values of liberal democracy, not because they are British, Swedish or somehow “ours”, but because they are universal and guarantee the equal liberty of the people who live here, and to ensure that anti-semitism in Europeans politics stays buried, as we had thought it had finally been after the Second World War.