The debate about pagan monotheism, which was sparked by the publication of Athanassiadi and Frede's Pagan Monotheism in Late Antiquity and the critical response that it provoked, has run for several years, and has led to numerous related publications. The span of these contributions is wide and extends from the ancient Near East and Egypt to ancient Israel and Hellenistic Judaism, and as far as classical Greece, the Hellenistic world and the Roman imperial period up to Christian late antiquity.

This contribution does not aim to undertake another thematic approach but to pose the basic question of what the ancient discourse between pagan and Christian monotheists was in fact about. Monotheism was already a topic for discussion between Christians and non-Christians in the imperial Roman age, and this lent an explosive quality to the issue of what could be called monotheism in antiquity. Both types of monotheism were defined by rapprochements and confrontations, and these brought a series of issues to the surface. What were the basic themes of this discussion? What were the front lines that were established in this debate? How did the disputants conceive their respective positions, and what were the charges they brought against one another? I tackle these questions in the context of two controversies: those between Augustine and the Platonists and between Celsus and Origen.