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.)
List of Dune religions
These Jewish communities are led by rabbis, at least some of whom have working relationships with the Bene Gesserit. "Heretics of Dune" suggests that Jewish thought may have influenced the development of Bene Gesserit philosophy. The Jewish community described in the novels defines itself as part of "Secret Israel", which, in conjunction with the sparse historical information given in the novel, suggests that the Jewish people had decided to conceal themselves to follow their religion and avoid the recurrent atrocities of their past. Long ago, the Bene Gesserit and the hidden Jewish communities came to an understanding of sorts: the Bene Gesserit would provide aid to hidden Jews if they were ever threatened, and help hide the fact that the Jewish religion survives in secret; in return, if ever a Bene Gesserit acolyte is lost and threatened on an isolated planet, the local Jewish community give her aid and shelter. A simple arrangement, but one which endured between both groups for millennia. Moreover, the Torah and Talmudic Zabur are listed in Appendix II of "Dune" as having contributed to the Orange Catholic Bible; the appendix also notes that these books were preserved on Salusa Secundus.