This Master's dissertation by Gavin Michal explores the historical and theological evolution of Jewish messianic movements from around 500 BCE through the 17th century, with a particular focus on the Sabbatian movement led by Shabbatai Tzvi (1626-1676). Michal argues that mysticism consistently precedes and fuels messianism, tracing early messianic claimants like Bar Kochva and David Alro'i, and emphasising the role of post-expulsion study circles in Spain. He delves into the fragmentation of Lurianic Kabbalah among the Ari's disciples, portraying it as a key catalyst for Sabbatianism's mystical fervor, innovations, and eventual underground persistence after Tzvi's apostasy to Islam. The study critiques various scholarly views on Sabbatianism's causes, defending Gershom Scholem's emphasis on Lurianic Kabbalah with modifications, while highlighting the movement's influence on subsequent Jewish ideologies, including Chassidism. In contrast to the mystical, supernatural messiah promoted by the Tosafists, Michal presents Maimonides' rationalist vision of a natural, non-miraculous messianic era as a theological counterweight, underscoring the tension between mystical and rationalist streams in Judaism. Through a descriptive, evaluative, and explanative methodology, the dissertation hypothesizes a direct link between successive mystical movements, concluding that Sabbatianism, far from an anomaly, was a pivotal force shaping modern Jewish thought. Michal proposes further research into its residual impact on Chassidism, emphasising the relevance of historical messianism to contemporary Jewish theology.