Early Christianity established itself primarily in cities – such as the Greek-speaking port cities on the Asian coastline, including Ephesus and Pergamon – rather than in remote rural areas. Cities, especially ports, were centers of commerce and trade, one of the classical means by which new religious and philosophical ideas were spread in the ancient world. The cities also offered a greater degree of anonymity than was possible in the countryside, allowing Christians to conceal themselves during an age that was generally hostile to their beliefs and practices. Christian communities were able to meet in secret, celebrate their beliefs, and begin to share their vision with outsiders.
The link between Christianity and the cities of the Roman Empire became so significant that the Latin term for a “country-dweller” (Latin: paganus) later began to be used in western Christian circles to refer to someone who retained older Roman religious beliefs, at a time when the empire had adopted Christianity as its official religion. A Latin term that originally lacked any religious associations of any kind thus came to refer to someone who practiced traditional forms of religion.
As Christianity became more deeply embedded in the imperial cities, a number of significant institutional developments began to take place. One was the rise of the “metro- politan bishop” – that is, a bishop who was seen as the titular leader of all the churches in a city, rather than of one specific Christian community. The most important of these were the bishops of Alexandria, Antioch, Constantinople, Jerusalem, and Rome. After the legalization of Christianity, these metropolitan bishops began to wield considerable politi- cal power – especially the bishop of Rome, who was seen as having a symbolic authority linked with the imperial authority of the city of Rome itself.