This broad-ranging study, the first full-length investigation of conceptions of faith and trust in the Judeo-Arabic tradition, explores a family of related concepts—faith (imān, emunah), conviction (i‘tiqād), and trust/reliance (tawakkul/ittikāl)—in Saadya, Baḥya, Halevi, Maimonides, Abraham Maimonides, and the Egyptian pietist circle of Abraham he-Ḥasid. The work points to a rich spectrum of conceptions of faith and trust—from the purely cognitive to the experiential and affective. What emerges are themes of faithfulness, loyalty, experiential certainty, and trustworthiness, expressed in devotion to a way of life that embodies these ideals. The virtue of trust expresses steadfast commitment to the truth. This study vividly illustrates the “Jewish-Arab symbiosis,” highlighting the shared spiritual language and rich, intertwined worlds of Islamic and Jewish philosophy, theology, and mysticism.