Küng’s assessment does not differ greatly from Protestant analysis. In A History of the Christian Church, Williston Walker notes: “Thus out of the struggle with Gnosticism and Montanism came the Catholic Church, with its strong episcopal organization, creedal standard, and authoritative canon. It differed much from the Apostolic Church; but it had preserved historic Christianity and carried it through a tremendous crisis.”
Incidentally, Küng notes that all three of the standards established by the church in the second century were attacked in subsequent ages. In the sixteenth century, the Reformation raised questions about the episcopal structure of Rome. The Enlightenment then questioned both the canon of Scripture and the creedal rule of faith.
The second-century church also made significant progress toward defining church life and Christian practice. Early in Christian history, the church made a distinction between proclamation (kerygma) and instruction (didache). The apostolic church was a missionary church, reaching beyond the borders of Judaism. The Gentiles were reached by the proclamation of the gospel in its basic outline. Stress was placed on the person and work of Christ—on His death and resurrection. When converts embraced Christ by faith, they were baptized and entered into the church community. Then they were given more thorough instruction in the faith. To this end, a manual of church order known as the Didache, or “The Teaching of the Twelve Apostles,” was composed in the second century.
This manual (discovered as recently as 1873) provides simple rules for local congregations, and deals with baptism, abortion (which was regarded as murder), almsgiving, fasting, the Lord’s Supper, and other matters. It sets two ways in stark contrast—a way of life and a way of death. Many of the admonitions found within it are explicit quotes from the New Testament Scriptures.
The Didache came to be used both as a catechetical tool and as a guide for Christian living. As such, it represents the first post-apostolic written code of Christian morality. Though it is not a part of the canon of Scripture, it offers valuable insights into the early church’s self-understanding.
The second-century church developed a strong sense of identity. This process continued well into the third century, when new heresies and new struggles with the state brought even more development and new structures in the church.