At Harvard University, the rabbi at a menorah lighting ceremony was unusually blunt.

“It pains me to have to say, sadly, that Jew hate and antisemitism is thriving on this campus,” Rabbi Hirschy Zarchi of Harvard Chabad said on Wednesday.

“Twenty-six years I’ve given my life to this community,” he said. “I’ve never felt so alone.”

Just the night before, he told the gathering, a woman passing by the Hanukkah candle-lighting ceremony yelled that the Holocaust was fake. When Harvard Chabad hosted a screening of an Israeli military film with footage from the Oct. 7 Hamas attacks, he said the campus police advised him to get security for his family. Even the giant menorah, prominently displayed in Harvard Yard, was packed away each night, he said, to protect it from vandalism.

Claudine Gay, Harvard’s president, stood nearby, waiting to light a candle. As the rabbi spoke, she stared straight ahead, looking stricken.

The uproar over Dr. Gay’s congressional testimony — on whether students would be punished if they called for the genocide of Jews — has exposed the deep anxiety, anger and alienation of many of Harvard’s Jewish students, alumni and faith leaders.

In interviews, many Jewish members of the Harvard community described their growing estrangement from campus. Protesters have disrupted lectures, shouting through bullhorns that the war in Gaza was a genocide. Antisemitic messages have been posted on social media. Some students have decided to check their Zionist beliefs in the classroom and in the residence hall. A few have traded in their kippas, or skullcaps, for baseball hats.

For students who are feeling increasingly isolated, it did not help that many of their Jewish peers had joined the pro-Palestinian demonstrations.