Judaism
Christianity was originally a sect of Second Temple Judaism, but the two religions diverged in the first century. The differences between Christianity and Judaism originally centered on whether Jesus was the Jewish Messiah but eventually became irreconcilable. Major differences between the two faiths include the nature of the Messiah, of atonement and sin, the status of God's commandments to Israel, and perhaps most significantly of the nature of God himself. Due to these differences, Judaism traditionally regards Christianity as Shituf or worship of the God of Israel which is not monotheistic. Christianity has traditionally regarded Judaism as obsolete with the invention of Christianity and Jews as a people replaced by the Church, though a Christian belief in dual-covenant theology emerged as a phenomenon following Christian reflection on how their theology influenced the Nazi Holocaust.
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.