The Pew Research Center found that 7 percent of Jews in the World War II generation describe themselves as non-religious. Among Millennials, 32 percent say they have no religion.
About 22 percent of all Jews say they have no religion.
"A Portrait of Jewish Americans," is the first major survey of U.S. Jews in several years, Pew said.
Almost two-thirds, 62 percent, of Jews say that being Jewish is a matter of identity and culture. But the survey found that Jews who identify themselves as having no religion are far more likely to intermarry and much less likely to raise their children as Jewish.
Reform Judaism continues to be the largest group of practicing Jews, with 35 percent identifying themselves as Reform, 18 percent as Conservative and 6 percent as Reconstructionist, Jewish Renewal and other smaller groups. Only 10 percent identify as Orthodox, but they tend to be younger and to have larger families.
The tendency of Orthodox Jews to abandon the tradition also appears to be slowing down with younger people more likely to stay.
Pew interviewed 3,475 Jews by telephone from Feb. 20 to June 13, 2013, after conducting 70,000 screening interviews. The margin of error is 3 percentage points.
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