Between the 1st and 3rd centuries AD, there was a rise in inscriptions dedicated to gods given the epithet hypsistos (“most high”). This growth raises questions about the beliefs and composition of the cult or cults that set up these dedications. The answers to these questions shed light on the construction and spread of monotheism in the pagan world as well as the context in which early Christianity spread and attracted followers. Many scholars, from Schürer in 1897 to Mitchell in 2010 have interpreted the Hypsistos inscriptions as evidence of a widespread pagan cult that practiced a syncretic Jewish-pagan religion and worshiped the Jewish god. In this essay, I examine Hypsistos inscriptions from the Bosporan kingdom, Anatolia, and Athens. Where possible, I infer the beliefs of the groups or persons that set up dedication, compare the iconography of the dedications, identify the gods of the inscriptions, often hidden behind a guise of anonymity, and explore the demographic composition of the groups that set up these shrines and dedications. I find that a variety of groups set up dedications to the Most High God, and that hypsistos connotes a number of different meanings. The beliefs of the worshipers that set up these dedications range from pagan polytheism to an extreme henotheism almost indistinguishable from monotheism. In some cases these worshipers may associate themselves with the Jewish religion, in other cases they do not. / Thesis / Master of Arts (MA)