This research investigates the causes underlying the absence of women in the Roman cult of Mithras (Mithraism), a mystery religion that systematically and completely excluded women from its rituals and membership. By synthesizing archaeological evidence with textual sources, this article argues that this exclusion was the result of a complex interplay of theological, social, and ritual factors. On a theological level, the profoundly androcentric mythology of the tauroctony and the exclusively male hierarchy left no symbolic space for female participation. Socially, its embeddedness within military networks and male collegia structurally precluded inclusion. Ritually, the ceremonies were designed around male identity and camaraderie. Through a comparative analysis with other contemporary mystery cults, this study highlights the exceptional nature of Mithraism's gender exclusion. The article concludes that this marginalization constrained the cult's social dynamism and contributed to its decline. Finally, a brief comparative glance is taken at the Islamic paradigm, where theological transcendence beyond gender and a structured legal framework (Sharia) provide a contrasting model for defining spiritual roles and participation, without ontological exclusion, within the concept of the Ummah.