From “Accounting for Jewish Secularism: Is a New Cultural Identity Emerging?” by Bruce A. Phillips. Source: Contemporary Jewry, Vol. 30, No. 1, Special Issue: Jewish Secularism (June 2010), pp. 63-85:
All Jewish immigrants, regardless of when they came, brought with them to America the experience of religion and ethnicity as an undifferentiated whole. The American Jewish experience can be understood as a series of institutional innovations that combine religion and ethnicity in evolving Jewish communal structures. In the early years of the American Republic Sephardic Jews used the synagogue as a communal institution (Sarna 2004). Eastern European Jewish immigrants similarly “transformed the traditional synagogue when they transplanted it in New York” into a communal institution (Moore 1981). In immigrant enclaves such as the Lower East Side these “Russian” Jews created hundreds of landsmanschaften, which combined ethnic and religious functions: “the landsmanschaft shul was a community reconstituted in the form of a synagogue, a ‘synagogue-community’ serving both religious functions of the synagogue and the social needs of the community” (Kaufman 1999, p. 170). As often as not, the landsmanschaft synagogue included a “bikkur cholim” or “gmilus chesed” which were respectively a mutual aid society and a free loan society (Tenenbaum, 1993) (Phillips, p. 66)
Another passage, later in the piece:
For well over a century, American Jews have expressed their ethnicity through their religion even while maintaining a worldview that is the most secular in America save for those without any religion at all. Moreover, Jews by religion run a close second to the most secular of Americans when it comes to belief in God and church/synagogue attendance. American Jews have not been particularly troubled by the apparent contradiction between their secular outlook and identification with a religion. This is because Judaism is based on the concept of peoplehood. Membership in the Jewish faith is conferred by birth, not belief (Phillips, p. 81).