Rabbi Rick Jacobs was installed Sunday as head of the largest Jewish movement on the continent, a ceremony that included cheers, ominous warnings and tearful, pleading prayers for his success.

Jacobs, 55, a Reform congregational rabbi known for his progressive politics and past as a modern dancer, told an audience of thousands something they already believe: The system most American synagogues use is broken.

Reform Judaism, with 1.5 million members, may be bigger than other branches of Judaism, including the Orthodox or Conservative movements, he said, but its youths are quicker to drop out. For decades, Jewish parents have treated synagogues like gas stations, dropping their kids off at feeble religious education classes to be filled up with “Jewish gas” but not becoming involved themselves, he said.

Too many synagogues demand financial commitments before creating relationships with potential members, he said, and too many focus only on the inside of synagogue walls even though more than half of American Jews aren’t members of a congregation.

“We are poised at one of the most critical and dramatic crossroads in all of Jewish history,” he said Sunday morning at the National Harbor Convention Center, where 6,000 people met at the biennial convention. His talk ended with his family and other clergy praying around him, saying “millions” were looking to him. His installation as the first new president in 16 years symbolizes the coming of new ideas.

Jacobs, the longtime leader of a suburban New York synagogue, won the position of president by arguing that Reform Judaism is potentially on the cusp of a “golden age.” The most progressive of the major branches of Judaism, it is welcoming to science, women, gays and lesbians, and ritual change. Openness to innovation and what Jacobs called “the greatest accumulation of Jewish wealth” in history position the movement perfectly to invest and thrive in contemporary culture, he said in an interview.

During the five-day meeting, the movement announced a multimillion-dollar campaign to connect with Jewish youths, only one in five of whom stay in the movement by the end of high school. Money around the country will go to new camps, new youth directors and mentoring for people working with the young.

Congregations also are hiring rabbis mandated to stay away from the synagogue and forge connections and social justice campaigns in the community. Small Sabbath get-togethers in homes are being held up as important as coming to synagogue.

Questions about how to keep members are plaguing organized American religion. Experimentation and intermarriage are common in the United States but are seen as more of a threat for Jews because the community is so small. Clergy of all faiths must deal with fickle, curious Americans, who are wary of joining things in general, even as those leaders hold fast to the houses of worship that are communal glue.

“It’s a 5,000-year-old maxim that Judaism happens in community,” Rabbi Jonah Pesner said of whether Jewish life requires a synagogue. “But that doesn’t mean you have to pay [membership] dues.” Pesner, director of the transition from retiring Rabbi Eric Yoffie to Jacobs, said the urgency to transform came from “a decade or two of young people asking excellent questions: From where do I get purpose? What does it mean to belong? Their answers are totally different from their parents’.”