That Christ Is One

In the fifth century, the Christian church faced a question that would define its faith for two millennia: is Jesus Christ one person with two natures, or two persons joined in one body? This is the book that settled the question. Cyril of Alexandria, the fiery patriarch who wielded political clout and theological brilliance like weapons, here combats Nestorius of Constantinople, who had dared to suggest that Mary bore merely a human Christ, not God himself. The controversy ignited over a single word - Theotokos, 'God-bearer' - but the stakes were nothing less than the identity of the incarnate God. Cyril's rigorous arguments, steeped in the Nicene tradition, established the metaphysical framework that Chalcedon would officially adopt seven years after his death: one person, two natures, inseparable and undivided. For anyone seeking to understand how orthodox Christianity came to understand Jesus - and why the doctrine of the Incarnation matters - this is the essential text, the weapon of choice in the most consequential theological battle of late antiquity.