The Pew Research poll also found a large increase in the number of interfaith marriages, which the study shows are more likely to produce children and grandchildren who are not raised as Jews.
The findings will likely prompt debate among Jews as to whether the trends reflect a triumph of acceptance and openness or portend an eventual fading of all but Orthodox Jewish life from America. The Orthodox make up just 10 percent of the population today, the poll shows, but are younger, more fertile and appear more committed to Orthodoxy than they were in the past.
The percentage of Americans who say their religion is Jewish has shrunk by about half over the past half-century, a conclusion similar to past research. While polls in the 1950s and 1960s said people who said their religion was Jewish made up about 3 to 4 percent of the country, today that percentage is 1.8, according to Pew. If people who have Jewish ancestry or who characterize themselves as culturally Jewish are added, however, the percentage rises to 2.2 percent.
Those numbers, experts said, reflect the particular complexity of counting Jews, whose identity encompasses a unique mix of religion, ancestry and culture. People who say they have no particular religion are growing in America in general — to 22 percent, coincidentally — but Jews are the least religious Americans by conventional metrics such as belief in God, importance of religion in their lives and worship attendance.
“The long-term question is, what is the composition of the Jewish population going to look like in 15 or 20 years given the pattern today? Smaller and more observant?” said Laurence Kotler-Berkowitz, senior director of research and analysis at The Jewish Federations of North America and Director of the Berman Jewish DataBank and a consultant to the Pew survey. “Or will Jews who are not Jewish by religion and who are intermarried, will they maintain some level of connection, and what will it be? These questions are all up in the air.”
So many Jews feel strongly about their identity as Jews but don’t define themselves by religion that Pew started using the academic term “Jews of no religion.” These are people who may attend synagogue, participate in Jewish rituals and see themselves as somehow Jewish even as they say they have “no religion.”
Pew went into much more detail than previous polls about the complicated and divergent ways Jews define Jewishness. Offered a list of attributes and asked which were “essential” parts of being Jewish, respondents first chose remembering the Holocaust, followed by “leading an ethical and moral life,” “working for justice and equality,” and “being intellectually curious.” Lower down, in order, were caring about Israel, having a good sense of humor, being part of a Jewish community and observing Jewish law.