This essay brings a process approach to the One-Many problem as treated in Gilles Deleuze’s thought, by focusing on the work of Ṣadr al-Dīn Muhammad al-Shīrāzī (Shiraz, 1571–1640). First acknowledging Avicenna’s concept of the univocity of being (attributed to John Duns Scotus) that influenced Deleuze, this essay examines how later Islamic philosophy, only recently transmitted to the West, provides methods for a lively process-based ontology. It compares Ṣadrā’s process cosmology to those of Gottfried Wilhelm von Leibniz and Alfred North Whitehead and examines his critique of abstraction in light of tashkīk, systematic ambiguity or modulation. The essay argues that Ṣadrā’s influence can make generative contributions to Deleuzean thought in terms of process realism, tashkīk as disjunctive synthesis, immanent causality, singularity, and an optimistic, world-oriented approach. Ṣadrā’s work allows us to rethink the boundary between philosophy and theology, and the essay proposes means to de-transcendentalize religious philosophy, if necessary.