What primarily makes someone Jewish — a sense of humor and an emphasis on justice work, or following Jewish law and believing in God? A new poll out Tuesday shows the first qualities are — for the moment — dominating American Judaism.

The percentage of Jews who identify as Jewish solely by culture or ancestry rather than religion has jumped from 7 percent to 22 percent since 2000, according to the poll, the first comprehensive survey of American Jews in more than a decade.

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.

It means different things to religious and non-religious U.S. Jews, according to a new poll. Percentage of respondents who said each of these is an essential part of what being Jewish means to them:

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.

Orthodox Jews rank following Jewish law far more highly than Jews in general do, as well as attachment to Israel and being part of a Jewish community.

In most areas, young Jews and older ones were similar. The largest gap between young and old was about caring about Israel. Among those 65 and older, 53 percent said caring about Israel is essential to being Jewish. Among Jews younger than 30, 32 percent feel this way.

There was also a gap on the topic of Israel between people who say they are Jewish by religion and people who define their connection with Judaism through culture or heritage. About half of Jews by religion say caring about Israel is essential, while 23 percent of Jews of no religion feel this.

The poll also shows 69 percent of Jews saying they are very or somewhat attached to Israel, which is “steady” when compared with other similar non-Pew research a decade ago, said Alan Cooperman, deputy director of Pew’s Religion & Public Life Project. The new poll also shows 43 percent of Jews have been to Israel.

The organized U.S. Jewish community has been very concerned about whether Jews are maintaining their connection to Israel, and the poll will further stir debate.

“Younger Jews are considerably less supportive of Israel’s policies and less supportive of Israel, and the differences are very large. I think we’re seeing a shift, not just a gap,” said Steven M. Cohen, a professor of Jewish social policy at Hebrew Union College-Jewish Institute of Religion and a consultant to the Pew poll.

The report will also add fuel to the ongoing debate about the impact of interfaith marriage. It finds that among married Jews who wed after 2005, 58 percent married non-Jews, compared with 17 percent of married Jews who wed before 1970. Pew was cautious with the numbers, noting its rates don’t include previous marriages including those that ended in divorce.

“Jews have had a rather low rate of intermarriage compared to Unitarians, Japanese Americans — other small groups,” Cohen said. “But for Jews, group survival has been an intrinsic part of their culture for 3,000 years or so. Will Jews survive is part of being Jewish. It may not be as big a part of being Japanese American or Methodist.”