Many progressive Jews are shocked that Black Lives Matter (BLM), a movement they support, has turned out to be virulently anti-Israel — to the extent that in its new platform, it charges Israel with “genocide” against Palestinians. Their response calls to mind an event of nearly 50 years ago. 

In 1970, the most famous American classical musician of the 20th century — Leonard Bernstein, the conductor of the New York Philharmonic and a major composer (“West Side Story,” operas, etc.) — along with other men of the left, both black and Jewish, threw what probably became the most notorious private fundraiser in American history at his Manhattan penthouse.

The honored guests were the Black Panthers, an America-hating, police-hating radical Black group, a sort-of predecessor to BLM. In the words of liberal writer Adam Gopnik in the latest issue of The New Yorker, the Panthers were “mindlessly cruel, misogynistic gangsters, capable of acts of torture and murder … ”

Here is how Panther leader “Field Marshall” Don Cox began the evening: 

“We call [the police] pigs. … We recognize that this country is the most oppressive country in the world, maybe in the history of the world. The pigs have the weapons and they are ready to use them on the people. … They are ready to commit genocide against those who stand up against them.”

Bernstein did not express a word of protest, let alone end the fundraiser, after hearing police labeled “pigs” and America labeled “the most oppressive country in the world.” In fact, Bernstein (who, to make the parallels even sharper, was very pro-Israel) pledged his entire fee for conducting the opera “Cavalleria Rusticana” to the Panthers. Four other prominent Jews — film director Otto Preminger, lyricist Sheldon Harnick (“Fiddler on the Roof”), lyricist and composer Burton Lane (“Finian’s Rainbow”) and renowned art dealer Richard Feigen — then made their pledges.

Prior to the Bernstein event, another Jew in the arts, film director and producer Sidney Lumet, also threw a party for the Black Panthers at his home. 

As New York Magazine reported:

“Ray ‘Masai’ Hewitt, the Panthers’ Minister of Education and member of the Central Committee … laid it on the line. … If buildings were burned and other violence ensued, that was only part of the struggle that the power structure had forced the oppressed minorities into.”

No country in history has treated its Jewish citizens as well as the United States has, yet left-wing Jews have supported almost every left-wing group that depicts America as an oppressor (and as war-mongering, imperialist, systemically racist, etc.).

But this love for the left has never been reciprocated. The left (not traditional liberals, it must be noted) has been Jew-hating (and later, Israel-hating) throughout its history.

Jews adored Karl Marx for well over a century, but that grandson of two Orthodox rabbis wrote one of the most influential anti-Semitic books of the 19th century (“On the Jewish Question”).

Shortly before he died last year, Robert Wistrich, the head of Hebrew University’s Vidal Sassoon International Center for the Study of Antisemitism, wrote a devastating book on left-wing anti-Semitism (“From Ambivalence to Betrayal: The Left, the Jews, and Israel”).

And one of America’s most prominent liberals, professor Alan Dershowitz, has just written an article titled “Are Jews Who Refuse to Renounce Israel Being Excluded From ‘Progressive’ Groups?”

Professor Dershowitz’s answer is, of course, yes. The “progressive groups” cited in the Dershowitz article have contempt for America — and America-hatred and Israel-hatred always go together.

“Last year,” Dershowitz wrote, “Rabbi Susan Talve, a longtime activist on race issues in the St. Louis area, was told that her advocacy for Israel was incompatible with the objectives of Black Lives Matter: ‘Solidarity from Ferguson to Palestine has become a central tenet of the movement’ she was informed, because ‘Israeli and U.S. state oppression are deeply interconnected.’ 

“Similarly,” Dershowitz noted, “a student who attended a Black Lives Matter rally at Northwestern University last year was told, ‘you support Israel, so you cannot also support us.’ ”

Dershowitz then lists other major left-wing groups that are anti-Israel: 

“MoveOn, CodePink, Occupy Wall Street, and Black Lives Matter [have] become openly opposed to the nation state of the Jewish people.”

And all these groups are supported by left-wing Jews.

Apparently, these Jews do not know a basic truth of history: An individual or group’s attitude toward Jews — and, today, the Jewish state — is one of the most accurate indicators of its morality.

When a group libels Israel with the charge of genocide, that group is by definition immoral. It is in the same moral category as those medieval Christians who came up with the infamous Blood Libel — the charge that Jews slaughter Christian children to use their blood to bake matzo. The only difference is that there were no Jews then who supported those Christians.

Dennis Prager’s nationally syndicated radio talk show is heard in Los Angeles on KRLA (AM 870) 9 a.m. to noon. His latest project is the Internet-based Prager University (prageru.com).