Judaism is the religion, philosophy, and way of life of the Jewish people. Judaism is a monotheistic religion, with the Torah as its foundational text, and supplemental oral tradition represented by later texts such as the Midrash and the Talmud. Judaism is considered by religious Jews to be the expression of the covenantal relationship that God established with the Children of Israel. Judaism includes a wide corpus of texts, practices, theological positions, and forms of organization. Within Judaism there are a variety of movements, most of which emerged from Rabbinic Judaism, which holds that God revealed his laws and commandments to Moses on Mount Sinai in the form of both the Written and Oral Torah. Historically, this assertion was challenged by various groups such as the Sadducees and Hellenistic Judaism during the Second Temple period; the Karaites and Sabbateans during the early and later medieval period; and among segments of the modern reform movements. Liberal movements in modern times such as Humanistic Judaism may be nontheistic. Today, the largest Jewish religious movements are Orthodox Judaism, Conservative Judaism and Reform Judaism.