For some - Jews and non-Jews, on the left and outside it - the election of Jeremy Corbyn to the Labour leadership is regarded as a disaster. Even had he not managed to win, the extraordinary outpouring of support for him that we have witnessed would have been seen as at least deeply disturbing.
Among the many criticisms aimed at Corbyn during his leadership campaign, the most divisive and emotive one is that he is someone who consorts with and provides political cover to antisemites, fundamentalists, homophobes and anti-democrats. For these reasons, Jews, and Jewish Labour supporters in particular, are among those who are most horrified by Corbyn's resounding win.
Of course, inevitably, given the bracing diversity of Jewish life, Jews have also been prominent among Corbyn's supporters and have been vocal in their denials that he is in any way a supporter of antisemitism. Nonetheless, given the cautiously liberal and openly Zionist tendencies that studies have shown prevails in British Jewry, it is fair to assume that Corbyn's Jewish supporters are a minority - albeit a highly significant one, and perhaps larger than many think - within British Jewry.
The anger and bewilderment that many British Jews feel towards the Corbyn ascendency is matched by a similar outrage by Corbyn's supporters, Jewish or not, that someone they consider a dedicated anti-racist should have been ''smeared'' in this way.
This leaves the mainstream Jewish community with a problem. For the first time in decades, a major British political party is being led by someone whose relationship with the British Jewish community is confined to one minority section of that community. Even if you think, as many do, that a Corbyn-led Labour party will be an electoral disaster, Labour will remain the second largest party for at least the next five years and will constitute a vital part of the political process.
It is not an encouraging prospect for the mainstream Jewish community to be cut off from a major part of the British political landscape.
So there is little choice but to ''reboot'' the Jewish community's relationship with Jeremy Corbyn and the fragile party that he now leads. But how? There appears to be so much bad blood that reconciliation seems impossible.
The road ahead is certainly difficult, but there are a number of reasons why the situation is not as hopeless as it appears. First, the Labour party's tradition of Jewish involvement is so long, deep and diverse, that, if Corbyn wishes to truly be an inclusive leader and attract those who supported his fellow leadership candidates Liz Kendall, Andy Burnham and Yvette Cooper, he will have no choice but to listen to the concerns of Labour Jews.
Labour needs to be a broad church, and it will be all but impossible to ''purge'' anti-Corbynite tendencies, at least in the short term, and if they themselves stay the course. After all, Corbyn himself survived decades of marginalisation within Labour and even New Labour had to throw the party's left wing the occasional bone.
Second, Corbyn's evident horror at being ''smeared'' as tolerant of antisemitism can, given imagination and willingness on all sides, be the starting point for dialogue. The difference between Corbyn and his detractors is not over the unacceptability of antisemitism, but over what constitutes antisemitism.
Without minimising the breadth of this divide, it may not be as unbridgeable as some think. Corbyn's history of dodgy contacts emerged during a time when he was marginal and largely ignored. Perhaps - and, yes, it is a big ''perhaps'' - with his actions and his contacts under unprecedented scrutiny, there might be the impetus for him to at least research his ''friends'' more assiduously.
Third, Corbyn has defended his choice of contacts as part of a strategy of openness and dialogue. He appears to be entirely sincere about this, despite his interlocutors being overwhelmingly clustered to one side of the political spectrum, at least in the case of Israel and the Middle East.
So why not try and nudge him towards pushing the envelope in selecting dialogue partners? As a marginal activist MP, nothing was pushing him into a genuinely broad and open engagement with a wide range of voices. As leader of the second largest British political party, who knows? At the very least, by taking Corbyn at his word, it may be possible to find out whether he is as committed to dialogue and conflict-resolution as he claims.
This, then, is the challenge for both Corbyn and for the Jewish community: can we open up a dialogue that may narrow the divide? Can he be encouraged to sit down with Zionists? With centrist and right-wing Israelis? With British Jews who have spent the past few months condemning him?
Let's hope so.