Florian Zacher: God’s substance, will, power and action in Marius Victorinus, Neoplatonic philosophy, Eunomius and Marcellus of Ancyra.

The interdependence of god’s substance, power, will and action is a common theme in Neoplatonic philosophy and Christian Trinitarian theology. Against the background of different philosophical conceptions from Plotinus, the anonymous Commentary on Plato’s Parmenides and concepts reported by Proclus, the specific profile of Victorinus’ Trinitarian theology is sharpened. Victorinus develops his Trinitarian theology as a specific interaction of three distinct activities, which only together constitute a single substance. An analysis of his place in the Christian debate on Trinitarian theology shows the specifically Christian motivation behind his concept. In contrast to Eunomius’ theology, a difference in action does not lead to a difference in substance, because the different actions are all necessary to constitute the single common substance. At the same time, the differentiation of inner activity in god’s substance is the foundation for the differentiation of his economic actions. The three hypostases can only act differently with regard to the world, because they act differently within god’s substance. Contrary to Marcellus of Ancyra’s concept, the difference in action is not only an economic broadening of the trinity to create and redeem the world, but an eternal inner process and the core of god’s substance. Placing Victorinus in the philosophical and theological debates of his time can show that the main motive for his Trinitarian theology is the soteriological question of man’s salvation.