People of Hebrew and Jewish religious descent have historically been outcasts or visitors in other lands. Taking Biblical history into account with scholarly history, it seems that Jewish people have always had trouble designating their ethnic and religious identities alongside people of other cultures. Since ancient times, there has never really been a "Jewish country," and even modern-day Israel is far-more multicultural than many other countries. Self-identification of Jewish heritage is problematic on many levels, and much of this stems from historically not having a proper homeland on which to base heritage. Israel, under attack for generations and not being a self-identified "Jewish state" until not even a century ago, is hard for Jews living in other countries to relate their identities to. In the book, Alaska has become a de facto "Jewish state," but is scheduled to be Reverted to U.S. control.
"...if we stay here, well, we are finished, too. Scattered to the winds. Reversion as the fire... a restored Jerusalem as the bucket of ice water. Some of our younger men argue for making a stand here, daring them to dislodge us. But that is madness."
(Chabon, The Yiddish Policeman's Union, Google Books)
As with the historical purges of the Hebrew people from Israel, this Reversion will remove the cultural heritage from an entrenched group of people; many of the Jews who leave Alaska have lived there all their lives, but the next generation will forget that place and become "scattered" into the Gentile world. Because of the need for a cultural identity, Reversion is seen by many as an unnecessary action; the law, they argue, should be changed to reflect the modern world. At the same time, they see Alaska as more of their homeland as Israel ever was. This makes the concept of self-identification as a Jew difficult at best, and the younger generation -- aside from the zealots and rebels mentioned above -- barely identify as Jewish at all.
This echoes modern-day Jews living in the U.S., many of whom are secular or do not even know of their heritage. Instead of looking for a cultural heritage to draw from, they accept identification with any number of other cultures or religious/ethnic groups, and so "scatter" their own culture farther and farther from its source. Instead of celebrating and passing on the culture of Jewish identity, secularists living in the U.S. seek to escape it, much as some in the book seek to forget their own heritage and "get along" with the rest of the world.