A curious thing happened in the hours following Monday’s launch of the (then) seven-member Independent Group of MPs. Many Jeremy Corbyn loyalists, bent on strangling this new initiative at birth, were at pains to separate one of the seven from the other six.

“With the exception of Luciana Berger…” became a common formulation, exempting the Liverpool Wavertree MP from whatever condemnation they were about to issue. While the other MPs could be written off as Blairites, careerists, neoliberals — insert your insult of choice — plenty of Corbynites were anxious to be seen to be respectful of Berger.

Respectful might be the wrong word. Rather, they were conscious that Berger’s stated reason for leaving Labour was her conclusion that the party was now “institutionally antisemitic” and they were keen to put that allegation to one side, where it could be safely ignored.

That way they could get on with the business of mocking the other six. Others condemned the ugliness of racially abusing a “heavily pregnant” woman, as if raining antisemitic abuse on a woman who was not about to give birth might be OK.

This desire to ring-fence Berger from the others was, in fact, a tacit tribute to her and the place she has earned in the national debate. It was an acknowledgement that the case she was making on Labour antisemitism — indeed the case she has come to embody— was fundamentally unanswerable.

Rather than challenge her contention that the party is now guilty of institutional anti-Jewish racism, they preferred to nod piously, perhaps add the odd platitude about “learning” or “listening,” and move on.

You can see why that seemed an appealing approach. To engage with what Berger had actually said, and indeed what she was doing, would have been to face something terrible.

The Community Security Trust’s Dave Rich, put it succinctly on Twitter: “Don’t underestimate the enormity of a Jewish MP forced to quit the party she has belonged to all her adult life due to the antisemitism she has faced *from within that party*. This is a shameful moment for Labour and a chilling moment for British Jews.”

Nor could you attempt to argue that Berger was wrong, at least not with a straight face. Less than 48 hours before the breakaway announcement, word emerged of a Labour member who had claimed at his local party meeting last August that “the Jewish community plans to attack our party” — and yet had faced no punishment, because, in the words of party officials, “the Labour party does not believe this is an incident of antisemitism.”

The case was as clear-cut as you could ask for. There was even an audio recording (including a Jewish Voice for Labour activist pleading that some Jews are not part of the conspiracy against Corbyn, many are good Jews, loyal and grateful to the leader — an activist, who despite his historically resonant protestations, earned no exemption from the attack). You could hardly ask for a clearer example of institutional anti-Jewish racism.

Nor was it really open to the loyal Corbynite to tell Luciana Berger she should stay and fight from within. Anyone who was at the Enough is Enough rally in Westminster 11 months ago will remember her standing before thousands of Jews, urging them to join the Labour party to fight this threat. It hardly endeared her to the crowd, but that was the case she made.

Don’t leave Labour, she said. Stay and fight from within. That’s what she did and for the best part of another long year, she stuck at it.

The “careerist” line of attack won’t really fly either. It’s hardly a career move to walk away from a party with a strong chance of forming the next government to join a group of seven whose prospects are, at least if history is any guide, next to non-existent. Instead, her critics have to face the uncomfortable truth that Berger has shown a quality that is vanishingly rare in British politics: courage.

Once elected in 2010, she could very easily have chosen the path trodden by plenty of Jewish politicians before her. She could have dialled down the Jewish thing; talked only about other issues, forged a different profile. She could have ingratiated herself with the new leadership, made the right noises to the Corbyn devotees. It wouldn’t have been so hard.

Even once she was deluged with anti-Jewish abuse, she could have swallowed it, rather than dragging it into the daylight so that others could see what antisemitism looks like in the raw. Because of course, every time she exposed the abuse she got, she got more of it.

This most recent choice of hers was only the latest in a series of choices she has made, each time taking the hard path when an easier one was available. After all that nonsense about Churchill, I’m rather against classifying people as heroes or villains. But if young Jews are increasingly coming to regard Luciana Berger as something of a heroine, as they are, you can see why.

Jonathan Freedland is a Guardian columnist