The emergence of Catholic Christianity
At least in an inchoate form, all the elements of catholicity—doctrine, authority, universality—are evident in the New Testament. The Acts of the Apostles begins with a depiction of the demoralized band of the disciples of Jesus in Jerusalem, but by the end of its account of the first decades, the Christian community has developed some nascent criteria for determining the difference between authentic (“apostolic”) and inauthentic teaching and behaviour. It has also moved beyond the geographic borders of Judaism, as the dramatic sentence of the closing chapter announces: “And thus we came to Rome” (Acts 28:14). The later epistles of the New Testament admonish their readers to “guard what has been entrusted to you” (1 Timothy 6:20) and to “contend for the faith that was once for all handed down to the holy ones” (Jude 3), and they speak about the Christian community itself in exalted and even cosmic terms as the church, “which is [Christ’s] body, the fullness of the one who fills all things in every way” (Ephesians 1:23). It is clear even from the New Testament that these catholic features were proclaimed in response to internal challenges as well as external ones; indeed, scholars have concluded that the early church was far more pluralistic from the very beginning than the somewhat idealized portrayal in the New Testament might suggest.
As such challenges continued in the 2nd and 3rd centuries, further development of catholic teaching became necessary. The schema of apostolic authority formulated by the bishop of Lyon, Irenaeus (c. 130–c. 200), sets forth systematically the three main sources of authority for catholic Christianity: the Scriptures of the New Testament (alongside the Hebrew Scriptures, or “Old Testament,” which Christians interpret as prophesying the coming of Jesus); the episcopal centres established by the Apostles as the seats of their identifiable successors in the governance of the church (traditionally at Alexandria, Antioch, Jerusalem, and Rome); and the apostolic tradition of normative doctrine as the “rule of faith” and the standard of Christian conduct. Each of the three sources depended on the other two for validation; thus, one could determine which purportedly scriptural writings were genuinely apostolic by appealing to their conformity with acknowledged apostolic tradition and to the usage of the apostolic churches, and so on. This was not a circular argument but an appeal to a single catholic authority of apostolicity, in which the three elements were inseparable. Inevitably, however, there arose conflicts—of doctrine and jurisdiction, of worship and pastoral practice, and of social and political strategy—among the three sources, as well as between equally “apostolic” bishops. When bilateral means of resolving such conflicts proved insufficient, there could be recourse to either the precedent of convoking an apostolic council (Acts 15) or to what Irenaeus had already called “the preeminent authority of this church [of Rome], with which, as a matter of necessity, every church should agree.” Catholicism was on the way to becoming Roman Catholic.