Judaism (from the Latin Iudaismus, derived from the Greek Ioudaïsmos, and ultimately from the Hebrew יהודה, Yehudah, "Judah"; in Hebrew: יַהֲדוּת, Yahadut, the distinctive characteristics of the Judean ethnos) is a monotheistic religion originating in the Hebrew Bible (also known as the Tanakh) and explored in later texts such as the Talmud. It has been defined ethnically as "the religion, philosophy, and way of life of the Jews" and religiously as "a covenant between God and the Jewish people that can be traced back to the prophets Abraham and Moses". Rabbinic Judaism holds that God revealed his laws and commandments to Moses on Mount Sinai in the form of both the Written and Oral Torah. This assertion was historically challenged by the Karaites, a movement that flourished in the medieval period, which retains several thousand followers today and maintains that only the Written Torah was revealed. In modern times, liberal movements such as Humanistic Judaism may be nontheistic.