A bomb just detonated in American Jewish life.

This month, the biggest Reconstructionist synagogue in America formally severed its connection with the national denominational organization, pointing to its seminary’s ongoing production of rabbis critical of Israel.

The dramatic public criticism from Kehillat Israel, a California congregation within the most progressive branch of mainstream Judaism, marks a significant turning point.

The grownups have shown up. Maybe it will help us fix the kids.

Rabbi Amy Bernstein of Kehillat Israel shared with The Post that her Pacific Palisades congregation, consisting of 930 families, was frustrated with Reconstructionist rabbis fostering hostility towards the community they are supposed to support.

“What they want is to use their title ‘rabbi’ to help Jews and non-Jews hate the idea of a Jewish democratic state. I don’t understand how you can do that and call yourself a leader of the Jewish people,” she said.

The break came after years of reflection, Bernstein said. “It broke my heart to say the movement has changed to the point that it’s not in line with our Reconstructionist values and tenets.” 

Mainstream American Jewry has long watched — often in dumbstruck silence — as progressive rabbis signed obscene petitions that make Jews less safe, helmed anti-Israel groups like Jewish Voice for Peace and took to the streets to demand “Palestine” be “free” of Jews.

The massacre of Israelis on Oct. 7, 2023, taught them nothing.

And while openly anti-Zionist synagogues are few, many rabbis in the Reform and even Conservative movements say their “big tent” requires embracing everyone — including those who advocate against Israel as a Jewish state. 

It’s a head spinner, all right.

Israel is mentioned some 2,500 times in the Hebrew Bible. It’s home to more than 7 million Jews, the majority of Jews worldwide.

Every day brings news of more incidents of Jew-hatred.

Meanwhile, rogue rabbis are lending a false patina of rabbinic authority to anti-Israel rhetoric — and confusing gullible youth.

Reconstructionism, founded in the 1920s by Rabbi Mordecai Kaplan, emphasized Jewish peoplehood, culture and evolving tradition.

The movement itself was never anti-Zionist. But with rabbinical seminaries competing for students, the Reconstructionist Rabbinical College outside Philadelphia has thrown open its doors to applicants making no secret of their disdain for Israel.

Reconstructing Judaism, which oversees the college and about 100 member synagogues, did not respond to requests for comment.

Kehillat Israel’s break means it will no longer send 1% of its annual budget to the umbrella organization.

Only about 3% of affiliated US Jews identify as Reconstructionist, yet some say that as Reconstructionist goes, so too goes the largest denomination, Reform Judaism, with roughly 2 million members.

“I’m really proud of Kehillat Israel,” Diana Fersko, senior rabbi at Manhattan’s Village Temple and author of “We Need to Talk About Antisemitism,” told The Post. “I’m hopeful it will inspire others.”

In the Reform world, charismatic rabbi and podcaster Ammiel Hirsch of Manhattan’s Stephen Wise Free Synagogue leads the charge to get the Union for Reform Judaism to draw the line on anti-Zionism. Reform seminaries also ordain anti-Zionist rabbis.

But don’t expect change from the top in that branch, either.

Andrew Rehfeld, president of the Hebrew Union College, made that clear last year at Hirsch’s annual conference, Re-CHARGING Reform Judaism.

“If we meet what we think is extremism with extremism of our own we will not only leave them to the radicals, we will betray our sacred values of liberalism,” Rehfeld told a packed, silent room. He might as well have been holding forth in some pretentious poli-sci grad-school seminar.

Every community has boundaries. Why the hell don’t we?

I’ve heard even worse at my own synagogue, Judea Reform in Durham, NC. At last year’s annual meeting, congregants were to vote on hiring a second rabbi, Hannah Bender. I had a question first.

“Does the rabbi identify as a Zionist?” I asked into the microphone.

The audience erupted. Synagogue executives whispered furiously.

Senior Rabbi Matthew Soffer rushed to a mic. 

There will be no “assigning litmus tests,” Soffer chided, “as we balance being proud — but not supremacist — about our Judaism.”

So now Zionists are supremacists — maybe like the Ku Klux Klan?

In fact, Bender had signed a petition disgustingly accusing Israel of “apartheid.” But my question was never put to her. 

Bender was confirmed:106 to 1. I was the sole “No.” Yet I am not alone.

Legions of us are fed up with anti-Zionism — and its toleration — in our supposed last safe space.

It’s time to act. Kehillat Israel has shown us how.

Kathryn Wolf was director of community engagement at Tablet and a staff reporter at the Miami Herald.