One of the women who was asked to leave the Dyke March, Eleanor Shoshany Anderson, couldn’t understand why she was kicked out of an event that billed itself as intersectional. “The Dyke March is supposed to be intersectional,” she said. “I don’t know why my identity is excluded from that. I felt that, as a Jew, I am not welcome here.”

She isn’t. Because though intersectionality cloaks itself in the garb of humanism, it takes a Manichaean view of life in which there can only be oppressors and oppressed. To be a Jewish dyke, let alone one who deigns to support Israel, is a categorical impossibility, oppressor and oppressed in the same person.

That’s why the march organizers and their sympathizers are now trying to smear Ms. Grauer as some sort of right-wing provocateur. Their evidence: She works at an organization called A Wider Bridge, which connects the L.G.B.T.Q. Jewish community in America with the L.G.B.T.Q. community in Israel. The organizers are also making the spurious claim that the Jewish star is necessarily a symbol of Zionist oppression — a breathtaking claim to anyone who has ever seen a picture of a Jew forced to wear a yellow one under the Nazis.

No, the truth is that it was no more and no less than anti-Semitism. Just read Ms. Shoshany Anderson’s account of her experience, which she posted on Facebook after being kicked out of the march.

“I wanted to be in public as a gay Jew of Persian and German heritage. Nothing more, nothing less. So I made a shirt that said ‘Proud Jewish Dyke’ and hoisted a big Jewish Pride flag — a rainbow flag with a Star of David in the center, the centuries-old symbol of the Jewish people,” she wrote. “During the picnic in the park, organizers in their official t-shirts began whispering and pointing at me and soon, a delegation came over, announcing they’d been sent by the organizers. They told me my choices were to roll up my Jewish Pride flag or leave. The Star of David makes it look too much like the Israeli flag, they said, and it triggers people and makes them feel unsafe. This was their complaint.”

She tried to explain that the star is the “ubiquitous symbol of Judaism,” and that she simply wanted “to be Jewish in public.” Then, she “tried using their language,” explaining “this is my intersection. I’m supposed to be able to celebrate it here.”

It didn’t work. Ms. Shoshany Anderson left sobbing. “I was thrown out of Dyke March for being Jewish,” she said. Just so.

For progressive American Jews, intersectionality forces a choice: Which side of your identity do you keep, and which side do you discard and revile? Do you side with the oppressed or with the oppressor?