Apparently, Seinfeld wasn't enough to keep American Jews from running out to buy Christmas trees. Or believing in Jesus Christ as the Messiah.

A new survey from the Pew Research Center's Religion & Public Life Project found that 32 percent of Jews had a Christmas tree in their homes last year, and that 34 percent say you can be Jewish and still believe in Jesus as the Messiah.

Jews becoming, well, less Jewish isn't a new trend. Drops in observance and increases in intermarriage have been well documented.

But this survey, which included 70,000 participants in all 50 states, is one of the most robust to date and underscores just how far the Jewish community has drifted from traditional religious roots. The survey found that only 31 percent of American Jews belong to a synagogue, and that 58 percent of all Jews (and 71 percent of all non-Orthodox Jews) intermarry. In comparison, before 1970 only 17 percent of all Jews married outside of the faith.

Generational differences are evident. Overall, 22 percent of all American Jews describe themselves as having "no religion," up from 7 percent in 2010. That population climbs to 32 percent for Jews born after 1980.

"It's a very grim portrait of the health of the American Jewish population in terms of their Jewish identification," Jack Wertheimer, a professor of American Jewish History at the Jewish Theological Seminary, told The New York Times.

Yet at the same time, despite a significant minority eschewing any religious connection, 83 percent of Jews of no religion say they are proud to be Jewish, while 42 percent say they still feel "a strong sense of belonging to the Jewish people."

So what does it mean to be Jewish, while having no religious identification?

What these numbers suggest is that Jews aren't becoming less Jewish, per se, but their definition of being Jewish is changing. They have shared values and history, if not religious beliefs.

For example, only 14 percent of all American Jews said observing Jewish law was an essential part to being Jewish. However, strong majorities said remembering the Holocaust and leading an ethical life were essential parts of being Jewish. Another 49 percent said being intellectually curious was an essential Jewish trait.

And unsurprisingly, 42 percent said having a good sense of humor was essential to being Jewish (thank you, Jerry). "For millennia, Jews knew who they were because they would stand out ethnically, linguistically, or religiously," writes Dan Friedman at The Washington Post. "But now in a multiethnic, multicultural America, there's no real way to know who you are. Whom you choose identify with might just as well be who has the same sense of humor."

Still, for Jewish advocates and experts worried about "Jewish continuity" — the maintenance of Judaism into future generations — humor is not enough to assuage their concerns that assimilation may eventually deteriorate a sense of Jewish identity. Josh Nathan-Kazis at The Jewish Daily Forward says:

Looked at one way, the fact that these young people consider themselves Jewish at all points to a growing diversity within the American Jewish community. Looked at another way, the fact that their ties to faith and community are so weak suggests that their Jewish identity is increasingly unimportant. [Jewish Daily Forward]

A love of Woody Allen movies or even a common commitment to ethics and education may not be enough to rewind assimilation, which is kind of like pushing toothpaste back into the tube. But Douglas Rushkoff at Time doesn't see this as cause for concern. He advises, "Spend as much time just doing and celebrating whatever Judaism means to you. The rest will follow."