Popular scholarship over the last 20 years or so has captured public attention by focusing on marginal or doctrinally suspect groups within early Christianity. Such scholars claim that these alternative forms of faith were just as authentic as early "orthodoxy"—and in some cases, perhaps even more so. These "lost Christianities" reveal that the earliest Christian church was not uniform but was rather like a religious kaleidoscope. Some recent books leave the impression that there were no shared definitions upon which most churches agreed. But do esoteric Gnostic texts or lost gospels mean that early Christians shared no common "core" of belief?

Such popular scholarship too often overlooks the fact that a common denominator of belief did exist in what ancient Christians called the "Rule of Faith" (in Latin) or the "Canon of Truth" (in Greek). This was a brief description of what Christians believed about God and his story of salvation. The Rule of Faith was what the church was preaching and teaching even before the various gospels and epistles then circulating became canonized into one "New Testament." Indeed, the way the New Testament was formed is part of the legacy that emerged from this early tradition.

The word delivered to us

The apostles themselves began to develop a norm or model for proclaiming the central doctrines of the Christian faith. Best known is Paul's brief citation of what he calls "tradition" in 1 Corinthians 15:2-8—that Christ died for our sins, that he was buried, that he was raised on the third day, etc. In Acts 2:33, Peter provides essentially the same points about the Messiah's crucifixion, resurrection, and exaltation to the right hand of God, "having received from the Father the promise of the Holy Spirit."

Within a few decades, these proclamations took the form of confessions, short formulas that were easy to remember and offered a basic structure for thinking about God. One such confession found in a Greek liturgical manuscript, called the Dêr Balyzeh Papyrus, was discovered in Egypt and probably written in the early second century:

I believe in God, the Father Almighty,
And in his only-begotten Son
  Our Lord Jesus Christ,
And in the Holy Spirit
  And in the resurrection of the flesh,
  And in the holy catholic church.

Around A.D. 125 or shortly after, Aristides of Athens wrote his Apology to the emperor in order to defend Christians against false accusations by giving a true account of what they believed. Aristides claimed that there was a "doctrine of the truth" preached by the apostles and still observed in his day:

Now the Christians trace their origin from the Lord Jesus Christ. And he is acknowledged by the Holy Spirit to be the Son of the Most High God, who came down from heaven for the salvation of men. And being born of a pure virgin, unbegotten and immaculate, He assumed flesh … and tasted death on a cross … and after three days, He came to life again and ascended into heaven.

The early church was committed to establishing standards for distinguishing true teaching and practice from false. As Bishop Polycarp of Smyrna admonished the Philippians, "Let us, therefore, forsake the vanity of the crowd and their false teachings, and turn back to the word delivered to us from the beginning."

A "canon" before the Canon

The first use of the term "canon" did not refer to Scripture, but to a condensed form of the church's oral tradition. In the opening of his Proof of the Apostolic Preaching, a handbook for teaching converts, Irenaeus of Lyons said Christians must adhere strictly to the "canon of faith" because it linked the churches of his day back to the apostles. He also called this simply "the preaching," "the faith," or "the tradition." Irenaeus articulated it this way:

God the Father, uncreated, beyond grasp, invisible, one God the maker of all … the Word of God, the Son of God, Christ Jesus our Lord, who was shown forth by the prophets according to the design of their prophecy and according to the manner in which the Father established; and through him [the Son] were made all things entirely … he became a man among men, visible and tangible, in order to abolish death and bring to light life and bring about communion of God and man. And the third is the Holy Spirit, through whom the prophets prophesied … and who in the end of times has been poured forth in a new manner upon humanity over all the earth renewing man to God.

Similar citations of the "Rule of Faith" are found in the second- and third-century writings of Hippolytus and Novatian in Rome, Tertullian and Cyprian in Carthage, and Origen and Dionysius in Alexandria. There was no one Rule of Faith, but many "rules" that differed in wording, style, and purpose, yet all shared basic characteristics. They were usually Trinitarian in format and included the birth, passion, and ascension of Christ. Some, but not all, referred to the second coming of Christ in glory, the final judgment, the resurrection of the body, and everlasting life for the saints.

More flexible than a creed or fixed formula, the Rule was easily adapted to many different contexts and circumstances. It presented those central elements that most churches professed—a summary narrative of God's self-revelation and his restoration of creation—a kind of "mere Christianity." Tertullian observed that the Rule was much like the four Gospels, which possess a basic unity of truth amidst their differences.

The exact origin of the Rule remains a mystery. Because of its flexible use and teaching-like format, it could have developed from summaries of the faith used to prepare candidates for baptism. Those who appealed to the Rule believed its affirmations were derived from the original message of the apostles. Irenaeus asserted, "The Church, though dispersed throughout the whole world, even to the ends of the earth, has received from the apostles and their disciples this faith."

Whose Bible?

Most commonly, Christian writers cited the Rule to defend the apostolic faith, often against different groups of Gnostic Christians. Irenaeus referred to the "canon of truth" several times throughout his anti-Gnostic work, Against Heresies. Gnostics argued that the Father of Jesus Christ was a different God from the Creator; this made Christ's salvation a denial or escape from creation. To this Irenaeus replied, "The disciple of the Lord, therefore, wanting to put an end to all such teaching" should adhere to the "canon of truth in the church." He then cited the first line of the "canon": "that there is one Almighty God, who made all things by His Word (Christ), both visible and invisible." This shows "that by the Word, through whom God made the creation, He also bestowed salvation on mankind included in the creation."

Many Gnostics were quite ready to use the Old Testament or Christian writings (as well as their own "scriptures") to defend their positions by reinterpreting the text to suit their cosmology. One Gnostic named Theodotus, for example, referred to the Father, Son, and Holy Spirit as "the names by whose power the Gnostic is released from the power of corruption"—meaning the divine spirit's escape from the material world. It became clear that it was not enough simply to appeal to Scripture to refute the Gnostics. Who could interpret the Bible rightly? Tertullian argued, "For only where the true Christian teaching and faith are evident, there will be the true Scriptures, the true interpretations, and all the true Christian traditions be found."

For the early church fathers, the Rule of Faith was a distillation of the fundamental doctrines in what would later become the New Testament. As such, it served as a measure of orthodoxy or a tool for interpreting Scripture correctly. The Rule was not something separate from or above Scripture, but a summary of the essential meaning of Scripture as it had been preached in the churches since the time of the apostles. This was a public or open tradition, as opposed to the secret tradition appealed to by the Gnostics. It shaped the way believers approached the texts, so that they read the Bible (especially the Old Testament) with Christ at the center.

Shared essentials

Throughout the first four centuries, the Rule was a unifying force in churches across the Mediterranean world. A letter from the council of Arles in Gaul (A.D. 314) to Sylvester, bishop of Rome, warned about the unstable minds of certain persons who "spit out the present authority, the tradition and the rule of truth of our God." Christians in southern France rightfully assumed that Christians in Italy knew and embraced the authority of the same Rule of Faith. A presbyter in Rome named Novatian (c. 245) preserved a shorter version of the Rule.

In sum, the Rule served as a plumb line of truth in a religiously pluralistic world. It possessed fixed and fluid elements that both represented and also helped shape Christian identity. Its widespread use demonstrates that the earliest Christians were very much interested in correct doctrine. The many citations of the Rule prove that the shared essentials of the church's tradition created a fairly cohesive platform of doctrinal norms to which Christians could appeal.

D. H. Williams is professor of religion in patristics and historical theology at Baylor University.

The rule of faith, indeed, is altogether one, alone immovable and unchangeable; the rule is as follows: believing in one only God omnipotent, the Creator of the universe, and His Son Jesus Christ, born of the Virgin Mary, crucified under Pontius Pilate, raised again the third day from the dead, received in the heavens, sitting now at the right (hand) of the Father, destined to come to judge living and dead through the resurrection of the flesh as well (as of the spirit).—Tertullian (c. 212)

The rule of truth requires that we believe, first in God and Father and Almighty Lord, the most perfect Creator of all things. He suspended the heavens above in their lofty height, made firm the earth with the heavy mass under it, poured forth the freely flowing water of the seas; and he arranged all these, in full abundance and order, with appropriate and suitable essentials.

The same rule of truth teaches us, after we believe in the Father, to believe also in the Son of God, Christ Jesus, the Lord our God, nevertheless the Son of God. We are to believe in the Son of this God who is the one and only God; namely, the Creator of all things, as has already been set forth above.

Next, well-ordered reason and the authority of the faith bid us (in the words and writings of our Lord set down in orderly fashion) to believe, after these things, also in the Holy Spirit, who was in times past promised to the church and duly bestowed at the appointed, favorable moment.—Novatian of Rome (c. 245)

Now to him who is able to open the ears of your hearts to receive the incisive words of the Lord through the Gospel and the teaching of Jesus Christ the Nazarene who was crucified in the days of Pontius Pilate, and slept, that he might announce to Abraham, to Isaac and to Jacob and to all his saints the end of the world and the resurrection that is to come for the dead, and rose from the dead, that he might show and give to us, that we might know him, a pledge of his resurrection, and was taken up into heaven by the power of God his Father and of the Holy Spirit, and at the right hand of the throne of God Almighty upon the cherubim, to him who cometh with power and glory to judge both the dead and the living, to him be dominion and glory, etc.—Teaching of the Apostles (third century)