Abstract: A study of the theological achievement of St John Damascene, set in its historical context. John Damascene was born between 650–75 in Damascus and died in or near Jerusalem about 750. His early life was spent as civil servant under the Umayyad caliphate, the rest as a monk in one of the monasteries of the Palestinian Desert. Palestinian monasticism had acquired a reputation of support for the Christian orthodoxy defined by the church councils of the Byzantine Empire, a reputation that it retained after the Middle East passed from the Byzantines to the Arabs. John Damascene is the most notable representative of this tradition. The bulk of the book explores in detail John's understanding of Christian Orthodoxy, as set out principally in his three-part Fountain Head of Knowledge. This includes the logical tools needed to argue theologically, set out in the first part, the Dialectica, an understanding of the nature and variety of heresy, in the second part, On Heresies, which includes the first Christian reflection on the new religion of Islam, and an exposition of Christian doctrine, in the third part, On the Orthodox Faith, which was to become immensely influential for all later Christianity, both East and West. Three final chapters discuss John's understanding of Christian art (icons), developed in opposition to Byzantine iconoclasm, his preaching, for which he was famous in his lifetime, and his enormous contribution to Byzantine liturgical poetry, especially the canon. A final chapter draws the threads together by means of a comparison between John Damascene and his nearly exact contemporary in the West, the Venerable Bede.

Keywords: Christian, iconoclasm, icons, liturgical poetry, monasticism, Palestine, preaching, theology, Umayyads