By the onset of the first century AD the Roman Empire included all the lands around the Mediterranean. Throughout this territory, whether in Europe, North Africa or the Middle East, early Christians endured terrible persecutions for their faith until in 313, during the reign of the emperor Constantine, the Edict of Toleration made Christian worship legal throughout the empire. By the end of the century Christianity had become the almost universal religion of the Roman world.
The word ‘catholic' means universal and all-embracing and was the word used to describe the original Christian Church. It was a universal Church, and the faithful travelled freely from one end of Christendom to the other. Tens of thousands of pilgrims travelled to the East to visit the holy sites and to obtain the blessings of monks and other holy ascetics there. ‘Not only do the inhabitants of our part of the world flock together', wrote the Syrian monk Theodoret of Cyrrhus (393-466) in his Religious History, ‘but also shmaelites, Persians, Armenians subject to them, Iberians, Homerites, and men even more distant than these; and there came many inhabitants of the extreme west, Spaniards, Britons, and the Gauls who live between them. Of Italy it is superfluous to speak.'
In what had already been the universal Roman Empire, Christianity added a new dimension of unity between the diversity of local cultures. Christian ideas and images were shared from the Thames to the Euphrates, from the Rhone to the Nile. Nor was the past forgotten; memories of the pagan gods still haunted the temples turned into churches, and the tombs and other places of pilgrimage often preserved, in Christian form, the immemorial beliefs and practises of a region. In those early days the only hint of a breach between the East and the West came in the arguments over the divine nature of Jesus Christ.