The Roman Church at the End of the Second Century

During the latter part of the second century Irenaeus of Lyons, at the beginning of his treatise “Against All Heresies,” did not hesitate to state with great emphasis that Christianity had fully succeeded in keeping intact the original Christian faith, in safeguarding the unbroken continuity of the apostolic tradition, and in maintaining the unity of belief and of sacramental practice throughout all the churches scattered in the Roman Empire. One might easily remark that the very treatise which Irenaeus had set himself to write offered clear evidence that the Christian unity so emphatically affirmed by him did not really exist. Far from being united, Christianity was rent by serious doctrinal and disciplinary conflicts. Evidently Irenaeus was speaking of the oneness of the Christian faith without taking into account the divergent beliefs and practices of those groups which had been cut off from the communion of the Great Church. So understood his assumption was true: by the end of the second century the καθολικὴ ἐκκλησία did possess unity of essential belief and even a certain degree of uniformity in its organization and practice. How such a unity had been achieved is one of the most important problems in the history of early Christianity.