Judaism
Around the 1st century CE, there were several small Jewish sects: the Pharisees, Sadducees, Zealots, Essenes, and Christians. After the destruction of the Second Temple in 70 CE, these sects vanished. Christianity survived, but by breaking with Judaism and becoming a separate religion; the Pharisees survived but in the form of Rabbinic Judaism (today, known simply as "Judaism"). The Sadducees rejected the divine inspiration of the Prophets and the Writings, relying only on the Torah as divinely inspired. Consequently, a number of other core tenets of the Pharisees' belief system (which became the basis for modern Judaism), were also dismissed by the Sadducees. (The Samaritans practiced a similar religion, which is traditionally considered separate from Judaism.)
Jewish atheism
There has been a phenomenon of atheistic and secular Jewish organizations, mostly in the past century, from the Jewish socialist Bund in early twentieth-century Poland to the modern Congress of Secular Jewish Organizations and the Society for Humanistic Judaism in the United States. Many Jewish atheists feel comfortable within any of the three major non-Orthodox Jewish denominations (Reform, Conservative, and Reconstructionist). This presents less of a contradiction than might first seem apparent, given Judaism's emphasis on practice over belief, with even mainstream guides to Judaism suggesting that belief in God is not a necessary prerequisite to Jewish observance. However, Orthodox Judaism regards the acceptance of the "Yoke of Heaven" (the sovereignty of the God of Israel in the world and the divine origin of the Torah) as a fundamental obligation for Jews. Even among non-Orthodox Jews, espousing atheism remains problematic outside of the Congress of Secular Jewish Organizations and the Society for Humanistic Judaism. The Reform movement, for example, has rejected efforts at affiliation by atheistic temples. The presence of atheists in all denominations of modern Judaism, from Secular Humanistic Judaism to Orthodoxy, has been noted.