History of the Catholic Church
The early Christian Church was not very organized. This resulted  in diverse interpretations of Christian beliefs. To have more consistency, by the end of the 2nd century Christian communities had developed a more structured hierarchy. The organization of the Church began to mimic that of the Empire. The churches in Antioch, Alexandria, and Rome were the most important. To solve problems about doctrine or policy, bishops often congregated in regional synods. This happened from the beginning of the 2nd century. By the 3r century,  the bishop of Rome began to be asked about problems that other bishops could not resolve.