This book describes the development of the Christian understanding of God from the second to the eighth century as witnessed by major theologians who gradually realized that the Incarnate Word made flesh was not the God of the philosophers. They helped construct the great dogmas of the Christological councils. Beginning with the Apologists and ending with Maximus Confessor, the theological tradition overcame the notion of impassible deity in favor of the humble God of Christian faith, the Word made flesh.