Ask people over 40 "Why be Jewish?" says Rabbi Eliyahu Stern, and they're likely to reply "What do you mean, 'Why be Jewish'? I was born Jewish."

"Peoplehood," Rabbi Stern calls it. But in the past two decades, a different kind of identity has emerged, and Judaism has moved "from an age of peoplehood to an age of meaning," says Rabbi Stern, who is coordinating the second annual "Why Be Jewish" conference for the Samuel Bronfman Foundation. The three-day conference begins Sunday at Deer Valley's Stein Eriksen Lodge.

A shared Jewish identity based on birthright — an identity that was once simply a given in people's lives — has eroded because of the rise of interfaith marriages, as well as increased social mobility and acculturation for Jews in America, Rabbi Stern says. With more choices available to them, and the ability to "walk out of Judaism," he says, "Jews have been beginning to construct their own identities based on what is most meaningful to them and, ultimately, what does Judaism provide them in their lives."

And out of that shift, Rabbi Stern says, have emerged "two very, very powerful groups, in some ways diametrically opposed to one another." One is what he calls "tribal," the other secular.

"These two groups will either reel off in radically different directions, never to meet, or, in a worst-case scenario, there will be a clash between them," Rabbi Stern predicts. "The same thing that is happening in the world at large is happening in Judaism today."

So one aspect of this weekend's conference, he says, is to ask, "What would a shared Jewish identity look like?"

The annual conference takes place in Utah, despite the relatively small Jewish population in the state, because Adam Bronfman, who sits on the board of the New York-based Bronfman Foundation, is a member and major supporter of Temple Har Shalom in Park City.

Although there will be a Monday lunch and discussion open to the community, the bulk of the conference is an invitation-only event. The 25 invitees include Jewish intellectuals from America, England, Italy, Israel and Poland. Topics will include the rift between religious extremism and secularism, the challenges of being a "hyphenated" Jew, the trend of secularism, what Jewry will look like in 2050, and "how is our children's Judaism different than ours?"