The rise of intermarried Jewish couples has prompted some rabbis, like Lewittes, to reimagine their roles as religious leaders—with job descriptions that aren’t primarily focused on the observance of Jewish law. “My success as a rabbi will be measured to the extent that I can help people access their own authentic understanding of themselves as Jews,” Lewittes said.

Those demographic changes were part of the reason why the rabbis at B’nai Jeshurun decided to start performing intermarriages. “The general stance has been that if we don’t do it, it won’t happen,” said Felicia Sol, one of the rabbis at the synagogue. “What the statistics show, and the reality on the ground, is that’s not true ... We could lose a generation, if not the future of Jewish life.”

Ultimately, though, the debate over intermarriage is not just a question of how best to get Jewish bodies into sanctuaries. It’s also about theology and law. While the Reform and Reconstructionist movements see intermarriage as theologically permissible, if discouraged, Orthodox and Conservative interpretations of Halacha, or Jewish law, see marriage between Jews and non-Jews as forbidden. Rabbis in those movements will typically only officiate if the non-Jewish spouse converts.

“To bless an intermarried union is … to in some way betray the very thing that I’ve given my life to, which is to try to maintain the Jewish tradition,” said David Wolpe, the senior rabbi at Sinai Temple in Los Angeles. “It may be beautiful, it may be loving, it may be worth celebrating on a human level. But on a Jewish level, it’s not fine, and it can’t be made fine.” Although rabbis would have to “have a heart of granite” not to feel sympathy toward young people who are in love and want to get married, “I don’t necessarily feel that someone else’s need is my obligation,” he said. “Someone else may need a rabbi to bless that union, or may want a rabbi to bless that union. It doesn’t mean that I have to do it.”

While the Conservative movement strives to welcome mixed families into congregations, schools, and summer camps, it has to do so “within the bounds of Jewish law,” said Julie Schonfeld, the head of the Rabbinical Assembly. “Judaism is fundamentally countercultural in that it’s all about boundaries.” While Conservative rabbis oversee a great number of “halachic, intensive conversions,” she said, there are limits to what the movement will do. “While emphasizing the openness of our communities to all who wish to come and worship with us, in regard to your question of whether the [Rabbinical Assembly] will consider permitting our members to perform intermarriages, the answer is no,” she wrote in a follow-up email after our interview.

The notion of legal boundaries is more complicated in Conservative Judaism than it is in Orthodoxy. The movement’s rabbis have generally argued that Jewish law can be reinterpreted and adapted in response to the challenges of modern life. Over the years, this has included approving same-sex marriage, popularizing mixed-gender prayer services, and letting women lead worship services and read from the Torah—Judaism’s sacred scrolls—on Shabbat and other holidays.