Origins of Judaism
For centuries, the traditional understanding has been that Judaism came before Christianity and that Christianity separated from Judaism some time after the destruction of the Second Temple in 70 CE. Starting in the latter half of the 20th century, some scholars have begun to argue that the historical picture is quite a bit more complicated than that. In the 1st century, many Jewish sects existed in competition with each other, see Second Temple Judaism. The sects which eventually became Rabbinic Judaism and Early Christianity were but two of these. Some scholars have begun to propose a model which envisions a twin birth of Christianity and Judaism rather than a separation of the former from the latter. For example, Robert Goldenberg (2002) asserts that it is increasingly accepted among scholars that "at the end of the 1st century CE there were not yet two separate religions called "Judaism" and "Christianity"".
Daniel Boyarin (2002) proposes a revised understanding of the interactions between nascent Christianity and nascent Rabbinical Judaism in Late Antiquity which views the two religions as intensely and complexly intertwined throughout this period.
American Jews
The survey found that of the 4.3 million strongly connected Jews, 46% belong to a synagogue. Among those households who belong to a synagogue, 38% are members of Reform synagogues, 33% Conservative, 22% Orthodox, 2% Reconstructionist, and 5% other types. Traditionally, Sephardic and Mizrahis do not have different branches (Orthodox, Conservative, Reform, etc.) but usually remain observant and religious. The survey discovered that Jews in the Northeast and Midwest are generally more observant than Jews in the South or West. Reflecting a trend also observed among other religious groups, Jews in the Northwestern United States are typically the least observant.