In 362/363 the Roman emperor Julian composed a treatise titled Against the Galileans in which he set forth his reasons for abandoning Christianity and returning to devotion to the traditional Greco-Roman deities. Sixty years later Cyril, bishop of Alexandria, composed a response. His resulting treatise Against Julian would dwarf the size of Julian's original work and in fact serves as our primary source for the fragments of it that have survived. Julian's treatise was the most sophisticated critique of Christianity to have been composed in antiquity and Cyril's rebuttal was equally learned. The Christian bishop not only responded directly to Julian's own words but drew upon a wide range of ancient literature, including poetry, history, philosophy, and religious works to undermine the emperor's critiques of the Christian Bible and bolster the intellectual legitimacy of Christian belief and practice. This is the first full translation of the work into English.