One protester labeled the baritone a “fascist.” Another called for the set to be “burned to the ground.” Others hinted they would try to disrupt opening night.

As the Metropolitan Opera prepares to stage John Adams’s critically acclaimed 1991 opera “The Death of Klinghoffer” on Monday for the first time, it has become enmeshed in a vitriolic debate that often seems to have more to do with the polarizing politics of Israel and the Middle East than the oratoriolike opera its singers have been rehearsing.

Many of the protesters, who want the Met to cancel “Klinghoffer,” have never seen the opera, which explores the murder of Leon Klinghoffer, a Jewish passenger in a wheelchair who was killed during the 1985 hijacking of the cruise ship Achille Lauro by members of the Palestine Liberation Front. The work has long aroused passions, but it has also been performed without incident in recent years. But the opera’s arrival at the Met — at a moment when many Jews are anguished by anti-Semitic incidents in Europe, reactions to the war this summer in Gaza, and videos of hostages being beheaded — has struck a nerve.

Angry protesters gathered across from the Met on the opening night of the opera season last month; a pair of public talks with members of the “Klinghoffer” creative team were quietly called off; and Peter Gelb, the Met’s general manager, said that he had received threats related to the production. He recently sent an email to the opera’s cast expressing regret that they had been subject to “Internet harassment” and defending the work from its critics, according to a copy obtained by The New York Times.