Syncretism occupies a contested but indispensable position in the depth-psychology corpus, functioning simultaneously as a historical description, a theoretical problem, and a normative charge. The term enters most forcefully through the study of Hellenistic religion, where Jonas, Campbell, and Jung each grapple with the fusion of Eastern and Western symbolic vocabularies that produced Gnosticism, Mithraism, and early Christianity. Jung offers the most explicit psychological gloss, defining syncretism as ‘growing together’ — a conglomeration of heterogeneous materials solidified into a new unity — and identifying Hellenistic syncretism as the matrix from which Catholic Christianity was codified. Campbell distinguishes a productive mythological syncretism, grounded in shared neolithic symbolic inheritance, from mere eclectic ‘hotchpotch,’ insisting that the cosmopolitan mythic lore of the Hellenistic period possessed genuine symbolic coherence. Jonas locates syncretism at the heart of Gnosticism’s irreducibility: the very fact of syncretism makes it impossible to explain Gnosticism by reference to its antecedents alone. King subjects the concept to ideological critique, showing how ‘syncretism’ has functioned polemically to police religious identity boundaries. Corbin, by contrast, explicitly refuses syncretism as a category, preferring ‘isomorphism’ governed by a common spiritual perception. Kohn documents syncretism as a living organizational principle in Chinese religious traditions. Together, these voices reveal syncretism to be not merely a descriptive term but a site of contestation over authenticity, origin, and cultural power.