Canon law was born in communities that felt great ambivalence about the relationship of law and faith. Custom governed early Christian communities, not a body of written law. It was custom informed by oral traditions and sacred scripture. Christians did not arrange their lives according to a Christian law but according to the spiritual goals of the community and of individual Christians. St Paul wrote to Roman Christians who knew and lived under the law created by the Roman state and reminded them that faith in Christ replaces Jewish law with a quest for salvation (Romans 7.1–12, 10.1–11). Law, he sharply reminded the Galatians, cannot make a man worthy before God; only faith can bring life to the just man (Galatians 3.11–12). After the apostolic age, Paul’s words were interpreted much more broadly. Later canonists applied them to secular law and even to canon law itself. They created a tension between the faith and conscience of the individual and the rigour of law that never has been and never will be completely resolved in religious law.

Christian communities lived without a comprehensive body of written law for more than five centuries. Consequently, in the early church, ‘canon law’ as a system of norms that governed the church or even a large number of Christian communities did not exist. To some extent the Roman state already regulated religious practice and so it quite naturally legislated for the church as the empire began to become Christian from the beginning of the fourth century. From the time of Constantine, Roman emperors issued decrees that regulated the affairs of the Christian church.