There’s a certain type of person you sometimes encounter in left-wing circles. It’s not that they’re anti-Semitic themselves, as such – at least they’d never admit to any sort of racial or religious prejudice ­– more that they don’t seem to take the issue quite as seriously as they might.

It’s likely they consider themselves a committed anti-racist and take pride in speaking out against bigotry. As such, if someone starts ranting about “Jewish conspiracies” or chucking around various dog whistle terms, they’ll probably make it clear they disagree. They just won’t necessarily consider it a red line.

They couldn’t imagine being drinking buddies with an EDL member, never mind comrades, but something about anti-Semitism is different. It’s a character flaw, but not a deal breaker. You can organise alongside someone who believes that Jewish people are malevolent parasites. If they occasionally opine that the Nazis were in cahoots with plotting Zionists, well, it’s embarrassing but what can you do?

I have no special insight into the process which led the Labour national constitutional committee to rule that Ken Livingstone shouldn’t be expelled from the party for his comments about Hitler and Zionism, but I have my suspicions. It seems likely there were people involved with exactly the sort of attitude I described.

Anti-Semitism isn’t unique to the left. Only a tiny minority of people I’ve encountered in my political life have expressed those kind of views. It’s not good enough, though, that such hatred is tolerated at all. It’s no good pointing to examples of racist incidents in other parties as evidence that Labour isn’t uniquely awful – that’s not how moral standards work.

If Livingstone had shown any inclination to apologise – if he’d made an active effort to reach out to the Jewish community and promised to educate himself on the issue – a temporary suspension would be somewhat easier to understand. There would be a logic to it. The expectation would be that by the time the ban was lifted, he’d be reformed.

As things are, the message seems simple: the committee just didn’t see his comments as that big a deal.

If the Labour party fails to take a zero tolerance approach to all forms of bigotry and hate, it’s not fit for purpose. If Jewish members feel uncomfortable or alienated it’s not an adequate vehicle for progressive change. Thankfully, the committee’s decision not to expel Ken has been condemned by a large number of Labour MPs and Corbyn has announced a further investigation. The reaction from some ordinary members, however, has been disturbing.

On social media I’ve seen Jewish comrades ridiculed and dismissed when they say that the ruling has concerned them. I’ve even watched people argue that Livingstone was just speaking the truth – a claim that every credible historian would dispute. These bigots and apologists might be in the minority, but their presence in the party is toxic.

Livingstone did all kinds of excellent things as Mayor of London, but that doesn’t somehow exempt him from the normal rules. His history and prominence are what make this case particularly important. It’s time for Labour to show, definitively, the sort of party it’s going to be. If Livingstone isn’t expelled I’ll be thinking seriously about ending my membership.

How can I allow an organisation that allows this kind of hatred to fester claim to represent me?