As Christianity spread, its converts included members from well-educated circles of the Hellenistic world, some of whom became bishops.
By the late first and early second century, a hierarchical and episcopal structure became clearly visible; early bishops of importance were Clement of Rome, Ignatius of Antioch, Polycarp of Smyrna, and Irenaeus of Lyons.This structure was based on the doctrine of Apostolic Succession in which, by the ritual of the laying on of hands, a bishop becomes the spiritual successor of the previous bishop in a line tracing back to the apostles themselves.According to Church tradition, it was under Nero's persecution that Peter and Paul were each martyred in Rome.Similarly, several of the New Testament writings mention persecutions and stress the importance of endurance through them.The earliest recorded use of the terms Christianity (Greek ).
Larger-scale persecutions followed at the hands of the authorities of the Roman Empire, beginning in the year 64, when, as reported by the Roman historian Tacitus, the Emperor Nero blamed Christians for that year's great Fire of Rome.
The matter was further addressed with the Council of Jerusalem.
(see Primacy of Simon Peter and Old Testament: Christian view of the Law for the modern debate.) The doctrines of the apostles brought the Early Church into conflict with some Jewish religious authorities, and this eventually led to the martyrdom of Stephen and James the Great and expulsion from the synagogues.
Each Christian community also had presbyters, as was the case with Jewish communities, who were also ordained and assisted the bishop; as Christianity spread, especially in rural areas, the presbyters exercised more responsibilities and took distinctive shape as priests.
Lastly, deacons also performed certain duties, such as tending to the poor and sick.
For 250 years Christians suffered from sporadic persecutions for their refusal to worship the Roman emperor, which Rome considered treasonous and punishable by execution.