The December election that now looks inevitable will be, as all elections are, a test. A test of a decade-old government that isn’t entirely sure what its achievements in office have been. A test of the public’s continuing appetite for Brexit and its tolerance for parliamentary histrionics. A test, too, of whether the country is ready to return to majoritarian government or whether volatile voter intentions and hung parliaments will be with us a while longer.

None of these is the most important metric. That dubious honour goes to the anti-Semitism test: will the UK put a party of Jew-haters into power? All of us will have to confront that test and each and every one will be judged on how they measure up. What is at stake is something far bigger than tax or education or even Brexit: the character of the country itself. The Labour Party has embraced ‘the organisation of politics against the Jews’ and the electorate will now decide whether that politics succeeds or is rejected. An unshakeable infamy lurks if we choose wrong.

The anti-Semitism test applies more acutely to the Labour Party, the largest and most successful anti-Semitic political party in Western Europe. Those we once flattered as ‘moderates’ turned out to be so fanatically attached to Labour that no outrage or indignity could prise them away. Their rationale was that they were ‘staying to fight’, resisting anti-Semitism and extremism from within, and that the Labour Party’s soul could be saved. Behold their victories manifold.

Until now, these matters could be brushed aside as academic but an election gives them practical import. Elections produce winners and losers (even if not always clear or resounding ones) and Labour ‘moderates’ now must choose: do they want Labour to win a general election? The question is inseparable from whether they wish to see Jeremy Corbyn become prime minister. The one wills the other.

It should hardly be shocking that Labour members would want the Labour Party, and therefore the Labour leader, to triumph. It is a perfectly legitimate view. It is not, however, one consistent with the opposition to anti-Semitism that Labour MPs and members avow. Campaigning to make Corbyn prime minister — which is what every single Labour campaigner will be doing — is campaigning to give a democratic mandate to anti-Semitism, to strip this bigotry of the opprobrium it has worked so hard to earn. There can be no mitigation. An accomplice is still an accomplice, even if he felt super conflicted while his mate was pistol-whipping the bank teller.

Corbyn’s accomplices insist they are preserving a post-Corbyn Labour Party and are staying to hasten his departure. An outside observer might cavil that this plan only works if Corbyn loses, but that is to misapprehend the psychology of the Labour tribalist. The party is pivotal to their identity; it is not just their life’s mission but, in many cases, their life. Getting Corbyn elected and re-elected, campaigning on his policies, voting for his legislation, but doing it all with a heavy heart — this is the Labour moderate’s idea of resistance.

The Labour party (1900 – 2015) is dead. It died the day a majority of members, £3 and otherwise, voted to make their leader a man already plainly drenched in the moral sewage of anti-Semitism. The Labour party (2015 -) is Corbyn’s party and if the famous centrists are working to preserve any party, it is that one. They might eventually salvage something out of it — Corbynism without Corbyn — but they will remain culpable for his actions until then.

Every vote for Labour is a vote for Corbyn. Every leaflet delivered is a two-fingered salute to British Jews. Every door knocked is a declaration: this is who I am and this is my tribe. You can campaign for Labour and vote for Labour without being an anti-Semite but in doing either you announce that you have reached an accommodation with anti-Semitism. Colluding in the organisation of politics against the Jews is worth it to get the railways renationalised.

The Labour party is going to fail the anti-Semitism test and the country might too.