Iamblichus' distinction between Theurgy and Theology

Iamblichus's distinction between theurgy and theology is crucial for understanding his Platonism. For theology was merely logos, a "discourse about the gods," and however exalted, it remained a human activity, as did philosophy. Theurgy, on the other hand, was a theion ergon, a "work of the gods" capable of transforming man to a divine status. Although the term theourgia originated with second-century Platonists to describe the deifying power of Chaldean rituals--some of which were believed to be transmitted by the soul of Plato himself--it was Iamblichus who provided a philosophic rationale for the performance of these rites and ensured that theurgy would become an integral part of the Platonic vocabulary. In Platonic terms, theurgy fulfilled the goal of philosophy understood as a homoiosis theo. The rituals themselves, Iamblichus explained, varied according to the capacities of its participants, and though he provided little information about particulars, it is clear that many "theurgic" rites were already well known to the Hellenic world. In the hands of Iamblichus, theurgy represented a revaluation of traditional cult practices. Iamblichus maintained that the divine principles invoked in these rites were exemplified abstractly and theoretically in the teachings of Pythagoras, Plato, and Aristotle, and that both cultic acts and philosophic paideia were rooted in one source: the ineffable power of the gods. In theurgy these divine principles were embodied and enacted, not merely contemplated, and in whatever context this occurred it was a "work of the gods," a theourgia in which the human soul participated both as recipient and beneficiary.
-Gregory Shaw, "Theurgy and the Soul"