In a scene in Itamar Moses’s new play, “The Ally,” a conservative Jewish student at an elite college asks why antisemitism is “invisible to the left until someone shouts ‘kill the Jews’ and sometimes even then!”

Mr. Moses, best known for his Tony Award-winning book for “The Band’s Visit” — a musical following Egyptian musicians and their Arab hosts in Israel — began taking notes for “Ally,” now having its world premiere at the Public Theater, seven or eight years ago. Yet the student’s question, like so many posed in the play, seems as timely as it is eternal.

“Ally” unfolds in September and early October 2023 — presumably intentionally just before Hamas’s attack on the Gaza envelope — on the campus of an unnamed but clearly prestigious institution. Its protagonist, Asaf, is at least roughly autobiographical: Like Mr. Moses, he’s a writer and teacher in his 40s who grew up at Berkeley, the son of Israeli immigrants. Early in the play, one of his pupils, Baron, who is Black, asks him to sign a document protesting the killing of a cousin by police officers.

Being a good liberal, Asaf, played here by the stage and screen actor Josh Radnor, consents to sign the “manifesto,” as it is called, but wishes to read it first. In doing so, he discovers one hitch: Within its 20 pages lies a passage criticizing our country’s association with Israel, using terms like “apartheid” and “genocide” to describe the latter nation’s policies.

Thus begins a string of events that will also find Asaf, who identifies as an atheist but carries a strong sense of his Jewish heritage, by turns grappling with and defending his beliefs, as much to himself as to others. Those views can be deeply conflicted, and Messrs. Moses and Radnor, abetted by Lila Neugebauer’s typically sharp direction, mine them for both poignance and comedy.

“I can see the need, given the extreme rightward tilt of Israel’s leading politicians lately, for pressure to move the needle back towards creation of a Palestinian state … which of course I also support,” Asaf assures his wife, who works for the college’s administration and is thus in a politically sensitive position. “And while divestment and sanctions are legitimate tools for applying that pressure — non-violent ones, which is great — doing it unilaterally, overnight doesn’t strike me as sensitive to the complexities of a region where many groups contribute to what’s happening.”

Before his wife can interject more than a word, Asaf adds, “But the real problem … what struck me as sort of weird is that Israel is the only country mentioned … in the context of America doing terrible things there … Israel is the only country whose own policies are condemned.”

Asaf’s language becomes less frank and even more tortured — at least initially — when he tries to express his support and his qualms to Baron, played by an affable Elijah Jones, and the community organizer for whom Baron is working, who happens to be Asaf’s ex-girlfriend, Nakia, portrayed by an elegantly self-possessed Cherise Boothe.

We also meet a ditzy progressive named Rachel, a junior at the school who is defying her fellow members of the Jewish Student Union by trying to get a controversial academic to speak on campus: not a right-wing hardliner — the kind of prospective speaker who is, in reality, most likely to get flak at a liberal arts college these days — but a Middle East scholar who has been critical of Israel. Played by a perky Madeline Weinstein, Rachel’s the kind of gal who uses terms like “whatabouting” and apologizes to anyone she perceives as having had more direct experience with discrimination.

The only other obvious Jew who turns up in “Ally” — Asaf’s agreeably pragmatic wife, played by a charming Joy Osmanski, is Korean-American — is that conservative student, a Ph.D. candidate named Reuven. An excellent Ben Rosenfield gets just one scene in the role, in which he storms arrogantly into Asaf’s office; after settling down and making a thorough and eloquent argument on behalf of Israel, and Jews generally, he makes a presumptuous and racist remark in reference to Baron’s late cousin, and walks out.

In contrast, a Palestinian American undergrad named Farid is introduced as humble and endearingly goofy in Michael Khalid Karadsheh’s graceful performance. When he does finally raise his voice to make his own, equally powerful speech, he seems so overcome with emotion that you may want to run up on stage and hug him. Asaf is literally left with his head hanging down.

I’m sure it was Mr. Moses’s honest intention to write a play that fairly represented all sides of a maddeningly complicated issue. And he deserves credit for at least acknowledging, as more Jewish writers have started to, that antisemitism is not purely a white nationalist problem — that it also has deep roots in progressive circles and disparate cultures — while also documenting the different kinds of racism that have tested alliances between Jews and other persecuted groups.

Yet “Ally” can suggest a progressive bias, or a sense that the playwright, like his central character, is concerned about sufficiently conveying his left-wing bona fides. Asaf alludes to a mix of fear and pride that is “thousands of years old and in my DNA,” but we get no real sense of how more recent and enduring examples of hate may have affected his own life.

Then again, maybe that’s part of Mr. Moses’s point: that Jews are encouraged, even expected, to place allyship higher than other groups do. Near the end of the play, Asaf seeks counsel from a rabbi, played by Ms. Boothe. She quotes the Talmudic sage Hillel the Elder, suggesting he ask himself, “If I am not for myself, who will be for me? If I am only for myself, what am I? And if not now, when?”

Only one character in “The Ally” is truly pressed to answer Hillel’s second question, and not surprisingly, he is a Jew. Still, Mr. Moses has crafted an engaging, challenging play that’s bound to ruffle everyone’s feathers at some point — and, overall, to promote empathy.