Some things in politics are far from being clear-cut. Here’s something that is. Luciana Berger, Labour’s MP for Liverpool Wavertree, is the victim of antisemitic abuse and harassment. She has suffered this for years. In October 2014, a neo-Nazi was jailed for sending her an antisemitic tweet. Another online troll was jailed for spewing racist bile at her two years later. Yet another was jailed in 2017 after calling Berger “Jewish scum” and suggesting she would “get it like Jo Cox”. Berger has used Twitter to highlight some of the vile antisemitic abuse she received – some of which looks like grotesque propaganda from 1930s Nazi Germany.

Berger has been courageous in confronting the hatred directed against her because she is Jewish, and not only deserves solidarity, but requires it. The horror of antisemitism cannot be minimised. Last year, there were 1,652 antisemitic incidents in the UK, a 16% increase on the year before, including verbal abuse on the streets. If you fail to extend solidarity to a victim of antisemitism because you do not agree with their politics, then you do not truly oppose antisemitism at all. Neither Labour’s leadership nor the vast majority of Labour members are antisemitic; but antisemitism does exist on fringes of the left, and there has to be far more seriousness in rooting it out. Those who deny it exists at all – who think it’s entirely a smear campaign and nothing else – are part of the problem.

Here’s something that is not so clear-cut. Luciana Berger’s local constituency Labour party has just tabled a motion of no confidence in her. An eclectic smattering of Labour MPs – including Chris Leslie and arch-Brexiteer Kate Hoey – have already lost such votes. Such motions are only symbolic, but indicate that there has been a collapse in trust among local activists in their MPs as candidates to advance the Labour cause.

Here’s the case of the local activists. When repeatedly pressed by LBC presenter Eddie Mair last month, Berger refused to say whether she thought Corbyn becoming prime minister would be good for Britain. Given this is an objective local activists dedicate much of their lives to – from parting with their money to knocking on doors on rainy evenings – there is clearly a collision of aspirations here. Labour MPs publicly making it clear they do not want their own party leader to become prime minister inevitably makes it less likely to happen.

There is also the fact that there are pretty solid grounds to suggest that Luciana Berger is involved in attempts to split from Labour and create a new party, something that she refused to deny this week. Clearly such an initiative would be an attempt to destroy the Labour party as an electoral force: again, something that is hardly going to endear its orchestrators to Labour members, including those who joined with boundless enthusiasm to campaign for a radical Labour government.

The new party would be doomed, of course: it would be lucky to get 5% in a general election. Berger herself benefited from Labour’s biggest voter surge since 1945 in the last election: her majority jumped by more than 5,000, and is 10,000 votes higher than the one amassed in the party’s 1997 landslide victory. Given just 6% of Labour voters reported voting for the party because of their local candidate, it is fair to say that a new party would be decimated in Liverpool Wavertree. But in polarised political times, if Labour lost just a handful of percentage points to a new party in key marginal seats, that could be enough to hand a majority to the Conservative party, which has brought Britain to the brink of national ruin. It is obtuse not to understand why this wouldn’t anger Labour members.

If any Labour member did want to expel Berger because she has spoken out about the antisemitic abuse directed against her, that would be despicable. In any case, Labour members in her constituency – however they vote in the no confidence vote – should passionately denounce the antisemitism she has suffered and express solidarity on that count without reservation. Despite their other justifiable grievances, they should also consider the optics of the situation.

That isn’t to say someone who is the victim of abuse should not be criticised. I confess, dear reader, that I have one or two critics out there: I would never argue that I should be immune from scrutiny because I receive homophobia and death threats every day, or because I have been repeatedly chased by far-right activists yelling things such as “Jonesy is a homo” and spitting down my neck while trying to punch me. That would be absurd.

How local party members express their democratic decisions is their own choice: it should be their right to decide which candidate best reflects their values and aspirations. But a decent approach would surely be for Berger’s party members – and indeed all of us – to show solidarity against Berger’s antisemitic harassment (which we should do whether Berger is in Labour ot not), and for Berger to commit to not join a new party and thereby attempt to destroy her own party. Is that not reasonable?

• Owen Jones is a Guardian columnist