Within Judaism there are a variety of religious 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, all or part of this assertion was challenged by various groups such as the Sadducees and Hellenistic Judaism during the Second Temple period; the Karaites during the early and later medieval period; and among segments of the modern non-Orthodox denominations. Some modern branches of Judaism such as Humanistic Judaism may be considered secular or nontheistic. Today, the largest Jewish religious movements are Orthodox Judaism (Haredi Judaism and Modern Orthodox Judaism), Conservative Judaism, and Reform Judaism. Major sources of difference between these groups are their approaches to Jewish law, the authority of the Rabbinic tradition, and the significance of the State of Israel. Orthodox Judaism maintains that the Torah and Jewish law are divine in origin, eternal and unalterable, and that they should be strictly followed. Conservative and Reform Judaism are more liberal, with Conservative Judaism generally promoting a more traditionalist interpretation of Judaism's requirements than Reform Judaism. A typical Reform position is that Jewish law should be viewed as a set of general guidelines rather than as a set of restrictions and obligations whose observance is required of all Jews. Historically, special courts enforced Jewish law; today, these courts still exist but the practice of Judaism is mostly voluntary. Authority on theological and legal matters is not vested in any one person or organization, but in the sacred texts and the rabbis and scholars who interpret them.