There is a Yiddish saying about the mysteries of faith, family and fellowship that, loosely translated, proclaims: "You cannot make Shabbat by yourself."
"The point is that you need the presence of other Jews around you to live out the dictates of your Jewish beliefs," said sociologist Steven M. Cohen of the Jewish Institute of Religion at Hebrew Union College.
Shabbat creates that circle of support. Beginning minutes before sundown on Friday, it involves a day of rest, prayer, ritual feasting and ties that bind. Some of these traditions are defined by faith while others are rooted in ethnicity and culture. But the whole ancient package assumes that Shabbat brings Jews together.
So what does it mean when the first major study of American Jews in more than a decade shows that -- even among Jews who call themselves religious -- only 33 percent believe being part of a Jewish community is "essential to being Jewish"? Only 23 percent of these "Jews by religion" considered it essential to follow Jewish laws.
The results in this Pew Research Center study were, of course, even more sobering among the rising number of Jews -- one in five -- who said they had "no religion at all."
"In theory, Jews who answer 'none' when asked about their religion can still be part of the wider Jewish community. There's nothing new about that," said Cohen in a telephone interview.
In practice, however, this "none" trend is viewed as negative by many Americans who consider the practice of Judaism to be a crucial part of Jewish identity, he said. Thus, the rising number of Jewish "nones" has many of the same serious implications as the much-discussed national rise in the number of religiously unaffiliated among people in general.
This national survey of Jews, by Pew's Religion and Public Life Project, is the first conducted by an institution outside the Jewish community. Jewish surveys in recent decades have consistently caused controversy because of fierce debates about how to define who is, and who is not, Jewish.
Among its headline-grabbing findings, this survey noted:
-- The percentage of adults who are "Jews by religion" has declined by about half since the 1950s. While 93 percent of "G.I. Generation" Jews call themselves religious Jews, only 68 percent of young "Millennial" Jews make that claim.
-- Only 15 percent of those surveyed said being Jewish is "mainly a matter of religion," as opposed to 62 percent who said Jewish identity is primarily about ancestry and culture. Two-thirds said it isn't necessary for Jews to believe in God.