Among the uglier manifestations of the new Labour establishment is a hatred of Israel so profound as to be indistinguishable from pathological anti-Semitism.
On Twitter, where hysteria and the herd mentality often dominate, Nora Mulready - who resigned from the party she loved over the Corbynites' extremism - demonstrates a rare combination of emotion and reason.
She has a great deal of courage too: defending Israel is not for the faint-hearted.
No one should forget, she says, "the unfathomable evil of the death camps and the Holocaust".
Yes, she says, to all those who downplay the unique suffering of the Jews, "gay people, communists, and Gypsies were victims of these camps, but the most bitter hatred of the Nazi regime was reserved, as we all know, for the Jews".
And so it was, yet that does not stop shrieking voices today comparing actions taken in self-defence by a vulnerable little state being compared to the Nazi conspiracy to murder every Jew they could get their evil hands on.
They might, suggests Ms Mulready, reflect on a "specific lesson learnt by Jewish people in the 20th century - six millions Jews were slaughtered, and no one came to help them".
She begs the enemies of Israel to imagine how they'd feel if within living memory their ancestors had been "burned to ashes, hanged, murdered" in their millions.
Would they not ensure that could never, ever happen again?
Many of the new Left have become unthinking supporters of Arab terror groups who openly admit they want to wipe out the state and its inhabitants.
I have a recurring nightmare that one day we will wake up to find Israel has been eradicated by a nuclear weapon and the West, as it did in the 1940s, is wringing its hands and saying "how did we let this happen?" as Hezbollah, Hamas, ISIS and all the other brainwashed Jew-haters dance for joy in the streets.
Last week there was a great deal of lazy, ill-informed and bigoted blaming of Israel for the deaths of Gaza rioters.
Can we just remember some relevant facts?
Israel is a legitimate, successful state which from its foundation has just wanted to be left in peace.
Yes, like millions of others at this time, hundreds of thousands of Palestinians were dispossessed, but it was the intransigence of their leaders that ensured that there was no compromise deal that would have been in everyone's interests.
Arab states who took in Palestinian refugees have kept them festering in increasingly overcrowded camps where they are promised that some day they will return to their homeland.
Periodically, Israel is attacked by some neighbours who become more bitter and resentful every time they are defeated.
Although few Israelis want more territory, after every invasion, for security reasons, they occupy more land.
Gaza had around 280,000 inhabitants in 1948 and now has close to two million.
In 2005 Israel packed up and left, but two years later Hamas violently seized control from Mahmoud Abbas's Fatah and uses its resources to dig attack tunnels, fire thousands of rockets at Israel and inculcate hatred in every new generation.
Less than a fortnight ago Hamas leader Yahya Sinwar incited a mass attack on Israel. "What's the problem with hundreds of thousands breaking through a fence?" he asked.
Since then tens of thousands of men, women and children - whose leaders regard them as cannon fodder - have tried to break through the barriers, often with the help of weapons like bolt-cutters, guns, knives and Molotov terror kites.
The objective of Hamas has been to abduct and kill any Israelis they can get access to.
The objective of the Israeli army has been to stop them doing so.
Rubber bullets and water cannon don't work at long range so the final line of defence had to be guns.
Of the 62 Gazans killed during this round of protests, 50 were Hamas terrorists and three Islamic Jihad.
This is a matter of survival.
Though not uncritical of Israel, like Ms Mulready I believe Jews are entitled to their homeland and have the right to protect the state and its people against those who would destroy it.
And like her, too, I hope a once decent party recovers its soul.