This first volume of the Penguin History of the Church looks at the beginning of the Christian movement during the first centuries AD and at the explosive force of its expansion throughout the Roman world. Drawing on recent historical research, Professor Henry Chadwick shows how Christianity had its roots in a synthesis of contemporary ideas and beliefs, and analyses the causes of its persecution under Diocletian, the fanaticism of its martyrs and its bitter internal controversies. The conversion of Constantine and the Edict of Theodosius meant that the Church had to reconcile its spiritual duties with a new, worldly role as an 'established church' for good government throughout the Empire. Professor Chadwick completes his history by demonstrating how this conflict of responsibilities led to the emergence of the Papacy and the monastic movement, the twin pillars of Christianity in the Middle Ages.