International gay leaders are planning a 10-day WorldPride festival and parade in Jerusalem in August, saying they want to make a statement about tolerance and diversity in the Holy City, home to three great religious traditions.

Now major leaders of the three faiths - Christianity, Judaism and Islam - are making a rare show of unity to try to stop the festival. They say the event would desecrate the city and convey the erroneous impression that homosexuality is acceptable.

"They are creating a deep and terrible sorrow that is unbearable," Shlomo Amar, Israel's Sephardic chief rabbi, said yesterday at a news conference in Jerusalem attended by Israel's two chief rabbis, the patriarchs of the Roman Catholic, Greek Orthodox and Armenian churches, and three senior Muslim prayer leaders. "It hurts all of the religions. We are all against it."

Abdel Aziz Bukhari, a Sufi sheik, added: "We can't permit anybody to come and make the Holy City dirty. This is very ugly and very nasty to have these people come to Jerusalem."

Israeli authorities have not indicated what action, if any, they might take to limit the events. Banning the festival would seem unlikely, though the government could withhold the required permits for specific events, like a parade.

Interfaith agreement is unusual in Israel. The leaders' joint opposition was initially generated by the Rev. Leo Giovinetti, an evangelical pastor from San Diego who is both a veteran of the American culture war over homosexuality and a frequent visitor to Israel, where he has formed relationships with rabbis and politicians.

Organizers of the gay pride event, Jerusalem WorldPride 2005, said that 75 non-Orthodox rabbis had signed a statement of support for the event, and that Christian and Muslim leaders as well as Israeli politicians were expected to announce their support soon. They said they were dismayed to see that what united their opponents was their objection to homosexuality.

"That is something new I've never witnessed before, such an attempt to globalize bigotry," said Hagai El-Ad, the executive director of Jerusalem Open House, a gay and lesbian group that is the host for the festival. "It's quite sad and ironic that these religious figures are coming together around such a negative message."

Rabbi Sharon Kleinbaum, co-chairwoman of the festival and the rabbi of Congregation Beth Simchat Torah, a gay synagogue in New York City, said the controversy was another sign that each religion had become polarized between its liberal and conservative wings.

The global Anglican Communion split deeply over homosexuality in the last two years after its American affiliate ordained an openly gay bishop and the Canada affiliate decided to allow blessings of same-sex unions.

"I reject that they have the right to define religion in such a narrow way," Rabbi Kleinbaum said of religious leaders who denounce homosexuality. "Gay and lesbian people are saying we are equal partners in religious communities, and we believe in a religious world in which all are created in God's image."

The festival is planned for Aug. 18-28 and is expected to draw thousands of visitors from dozens of countries. The theme is "Love Without Borders," and a centerpiece will be a parade on Aug. 25 through Jerusalem, a city that remains deeply conservative, though other parts of Israel have become increasingly accepting of gays in recent years. Other events include a film festival, art exhibits and a conference for clerics.

When the first WorldPride festival was held five years ago in Rome, religious opposition came from the Vatican, while secular opposition came from a neo-Fascist group that vowed to hold a counterdemonstration. But the neo-Fascists canceled their demonstration, the march came off peacefully, and even a few center-right politicians joined many thousands of marchers.

One day later, however, Pope John Paul II appeared on a balcony over St. Peter's Square and delivered a message expressing his "bitterness" that the gay festival had gone forward, calling it an "offense to the Christian values of a city that is so dear to the hearts of Catholics across the world."

Both WorldPride festivals were initiated by an umbrella group, InterPride, that says its mission is to promote gay rights internationally.

The outcry over the 2005 festival will not be confined to Israel. The American evangelical leader who helped to galvanize the opposition, Mr. Giovinetti, is the senior pastor of Mission Valley Christian Fellowship, an independent church that meets in a hotel in Southern California. A former band leader in Las Vegas, he is also host of a radio program heard on stations around the United States.

Neither he nor other evangelical American leaders were at the news conference in Jerusalem, which was called by the chief rabbinate of Israel. But by all accounts Mr. Giovinetti played a crucial role in spreading the first alarms among religious leaders about the gay festival.

He said he had first heard about WorldPride from a congregation member who had told Mr. Giovinetti that he was gay for many years and still monitored gay Web sites. Mr. Giovinetti said he alerted Israeli politicians and religious leaders.

Mr. Giovinetti circulated a petition against the festival, titled "Homosexuals to Desecrate Jerusalem," which he said had been signed by every member of the ultra-Orthodox Shas Party in the Israeli Parliament. Another American who helped bring together the opposition was Rabbi Yehuda Levin, of the Rabbinical Alliance of America, which says it represents more than 1,000 American Orthodox rabbis. At the news conference in Jerusalem, he called the festival "the spiritual rape of the Holy City." He said, "This is not the homo land, this is the Holy Land."

Annual marches by homosexuals have become routine in Tel Aviv, a secular coastal city. For the past three years, gay parades have also been staged in Jerusalem. Religious groups have complained, but the police have issued permits for the events, which have been held without any serious incidents.