The “Regula Fidei” and Its Implications for “Sola Scriptura”


This article will explore the implications of the early New Testament Church’s reliance upon the regula fidei (“rule of faith”) on the Reformation concept of sola Scriptura.  To do so, we will first consider the history of the regula fidei and how it relates to the founding of the first Christian congregations.  Then, we’ll consider the development of the Biblical New Testament canon of Scripture.  Finally, we’ll close with the main point of this article which is to look at the implications of all of this for sola Scriptura.  This article is no an exhaustive study, but rather is meant to stimulate thought and discussion.

Christian Congregations Founded on the Teachings of the Apostles

The first essential point to appreciate about the early New Testament Church is that the congregations based their core beliefs on the teachings of the Apostles.  St. Paul, for example, reminds the Corinthians of what he had taught them.  He calls this the message of “first importance,” writing that he taught them “that Christ died for our sins in accordance with the Scriptures, that he was buried, that he was raised on the third day in accordance with the Scriptures,” and that he appeared to many, including Paul (1 Corinthians 15:3ff).  Paul mentions the “Scriptures,” and at the time of his writing this letter (mid-50s AD), this would have meant what we now call the Old Testament.  

There are two take-aways from this.  First, that Paul was stating that Christ fulfilled the promises and prophecies given in the Old Testament.  Second, that the teachings of the Apostles did not directly derive from the New Testament, since the writings which would become the New Testament were still being composed (indeed, Paul’s letters would become part of the canon).  Thus, the salient point is that the Apostles’ teachings came from Jesus Christ himself and were then imparted to the congregations they founded and that they were in accordance with God’s promises given in the Old Testament.  

Due to the importance of the Apostles in founding the congregations, their teachings gave rise to what was called the “regula fidei” or the “rule of faith.”  This summary was based on the apostolic teaching and was the standard by which other doctrine was judged (thus, “rule” in the sense of “ruler” or something by which other things are judged).   Each local congregation within the Church had its own rule of faith which was a succinct statement of the essentials of what the apostles taught.  While each congregation had its own “rule,” they were all basically the same.  Each rule of faith focused on the Holy Trinity and the role of each Person in our salvation: the Father who created all things, the Son Jesus Christ who died and rose to restore all things, and the Holy Spirit who spoke through the prophets and gathers together the Church in faith.  These were the essentials; some of these three articles of the rule would be expanded in certain localities in order to combat whatever heresy was most prevalent in the area (for example, the first article concerning the Father was elaborated upon in areas where Gnosticism was a threat, in order to affirm the goodness of creation since Gnostics believed that the material world was intrinsically evil).

St. Irenaeus includes a rule of faith in his book Against the Heresies (chapter 10).  Irenaeus was the bishop of what is now Lyon, France in the 2nd Century AD.  He wrote the following (note that “Economies” in the context of what Irenaeus writes means the way that God has ordered salvation):

The Church, indeed, though disseminated throughout the world, even to the ends of the earth, received from the apostles and their disciples the faith in one God the Father Almighty, the Creator of heaven and earth and the seas and all things that are in them;

and in the one Jesus Christ, the Son of God, who was enfleshed for our salvation;

and in the Holy Spirit, who through the prophets preached the Economies, the coming, the birth from a Virgin, the passion, the resurrection from the dead, and the bodily ascension into heaven of the beloved Son, Christ Jesus our Lord, and His coming from heaven in the glory of the Father to recapitulate all things, and to raise up all flesh of the whole human race, in order that to Christ Jesus, our Lord and God, Savior and King, according to the invisible Father’s good pleasure, ‘Every knee should bow of those in heaven and on earth and under the earth, and every tongue confess Him…

Irenaeus adds:

The Church … though disseminated throughout the whole world, carefully guards this preaching and this faith which she had received, as if she dwelt in one house.  She likewise believes these things as if she had but one soul and one and the same heart; she preaches, teaches, and hands them down harmoniously, as if she possessed but one mouth [emphasis added].

Irenaeus then goes on to explain that the churches in Germany, Spain, Gaul, Libya, and all throughout the world proclaim the same faith that was handed down to them by the Apostles.  A “message of first importance” which came from Jesus Christ, given to the Apostles, and entrusted to the Church, wherever she may be found.

Justin Martyr, who lived in the second century as well, in his letter to the Roman emperor (the First Apology) also mentioned the faith of the Church.  He wrote about the promise of the resurrection of the body and life everlasting and said (chapter 13):

Our teacher of these things is Jesus Christ, who was also born for this purpose, and was crucified under Pontius Pilate, procurator of Judaea in the time of Tiberius Caesar; and we will show that we worship him rationally, having learned that He is the Son of the true God Himself, and holding Him in the second place, and the prophetic Spirit in the third rank.

Justin Martyr then spends the rest of his book explaining this mystery that was handed down to him from the apostles.

Tertullian, living around the same time, in his book Against Praxaes also mentions the “rule of faith” in an effort to refute Praxaes’ heretical views:

We, however, as we indeed always have done (and more especially since we have been better instructed by the Paraclete, who leads men indeed into all truth), believe that there is one only God, but under the following dispensation, or οἰκονομία, as it is called, that this one only God has also a Son, His Word, who proceeded from Himself, by whom all things were made, and without whom nothing was made. Him we believe to have been sent by the Father into the Virgin, and to have been born of her — being both Man and God, the Son of Man and the Son of God, and to have been called by the name of Jesus Christ; we believe Him to have suffered, died, and been buried, according to the Scriptures, and, after He had been raised again by the Father and taken back to heaven, to be sitting at the right hand of the Father, and that He will come to judge the quick and the dead; who sent also from heaven from the Father, according to His own promise, the Holy Ghost, the Paraclete, the sanctifier of the faith of those who believe in the Father, and in the Son, and in the Holy Ghost. That this rule of faith has come down to us from the beginning of the gospel, even before any of the older heretics, much more before Praxeas, a pretender of yesterday, will be apparent both from the lateness of date which marks all heresies, and also from the absolutely novel character of our new-fangled Praxeas.

Within the writings of Irenaeus and Justin and Tertullian, then, we see the “rule of faith” as the reflection of Apostolic teaching.  Eventually, the “rule of faith” of Rome would become known as the Old Roman Creed, leading to the Apostles’ Creed we know today.  When looking at the Apostles’ Creed, one can see that it is the same teaching as that found in the early “rules of faith.”

The Development of the Biblical Canon

What was the “rule of faith” used for in the congregations of the early Church?  

For one, they were used to judge teaching to see if it was in accord with the Apostles’ teaching.  As Paul wrote to the Galatians: “But even if we or an angel from heaven should preach a gospel contrary to the one we preached to you, let him be under a divine curse! As we have said before, so now I say again: If anyone is preaching to you a gospel contrary to the one you embraced, let him be under a divine curse!” (Galatians 1:8-9).  

Another important use in the early Church for the “rule of faith” was in judging writings.  This led to the development of the New Testament canon.  The point is that as writings were circulated among the congregations, they used their “rule of faith” to determine which writings were truly apostolic and thus Scriptural.  The key factor in the early Church’s determination of what was Scripture and what was not was apostolic authority; i.e. was a writing connected to an Apostle and did it reflect apostolic teaching?  Thus, writings such as “Shepherd of Hermas,” “Didache,” and “1 Clement” were considered inspired and sometimes used by congregations, but they were not considered part of the Scriptural canon as they were not directly connected with the Apostles.  Paul’s writings, the four Gospels, and the other books accepted as the New Testament were Scripture, because they were Apostolic (Mark and Luke’s Gospels owing to their close connection with Peter and Paul).

The importance of apostolic authority can even be seen in the negative witness of the heretical Gnostic writings.  The point is that they named their writings after apostles in an effort to get their writings accepted as Scripture; their actions are a testament to the fact that apostolicity was the key criteria for a writing to be accepted by the Church.  The Church, however, recognized that the teachings in these writings did not accord with their “rule of faith” and so rejected them.

Thus, when the Council of Nicaea met in 325 AD, they did not “invent” the New Testament out of whole cloth.  Rather, they formally ratified a Biblical canon that was already known and used throughout the Church because the individual books had been judged to be in accord with apostolic teaching as codified in the “rule of faith.”  Thus, both the “rule of faith” (and later Creeds) and the New Testament were derived from apostolic teaching and authority, in parallel.

Implications for Sola Scriptura

Given that the “rule of faith” and the New Testament arose in parallel, what does this mean for the Reformation doctrine of “Sola Scriptura?”

First, what is “Sola Scriptura?”  It is the concept of “Scripture alone;” i.e. that all teaching and authority ultimately derives from the Bible as its primary source.  Oftentimes, it is also closely connected with the concept of the “perspicuity of the Scriptures;” that is, that the Bible can be interpreted clearly by individuals.  It therefore rejects the concept of a Church “magisterium” which provides approved interpretations and teachings as well as the closely-related Catholic concept of Sacred Tradition.  

However, in practice, Protestant churches do operate with a sort of “rule of faith” to guide Scriptural interpretation, even if they state that these rules of faith are subservient to the Scriptures.  Lutheran churches use the “Book of Concord” as their main confessional document and ordained pastors are required to subscribe to it; it is meant to provide a norm for Biblical interpretation.  Reformed churches use the “Westminster Confession of Faith.”  Baptist churches use various confessional statements. 

Thus, the effect of confessional documents and creeds is to provide a rule of faith by which Scripture is interpreted.  These documents serve as the norm by which interpretations of the Bible are judged to see which ones are within the realm of orthodoxy and which are heterodox or heretical, at least as considered by the individual denomination or congregation.  In this, they serve much the same function as the early “rules of faith” as well as the Creeds.  They also serve to check private Biblical interpretation by providing the boundaries, as it were, for what is accepted by the Church and what is rejected.

This check on private Biblical interpretation is entirely useful, as the witness of the Church is required in order to faithfully interpret Scripture; otherwise, false interpretations, schisms, and heresies occur.  In addition, the Scriptures were given to the Church and belong to her, not to any individual believer.  Stated another way, believers have a duty to listen to the Church’s teaching and let it be a guide to their own interpretation, rather than disregarding the historic teaching of the Church in favor of their private opinion.  

Given that Protestants have their own form of tradition by which they interpret Scripture, would it then be more in line with Christian charity to view the Roman Catholic Church’s views on Scripture in a similar light?  The Catholic Church believes in Sacred Scripture as well as Sacred Tradition, both arising in parallel from apostolic teaching and authority.  Catholics are careful to point out that Sacred Tradition does not introduce new teachings or revelations, but rather that it interprets the “deposit of faith” given to the Church by the Apostles.  Protestants in practice believe something similar, as the Creeds and confessional documents are used as statements of faith and interpretive guides to the Scriptures.


More could be said about the early Church’s use of the “rule of faith” and the subsequent development of the New Testament canon.  However, this article is meant to provide some thoughts and discussion points to consider whether or not the Protestant and Catholic views on the Scriptures are not closer to each other in practice than commonly assumed.  In addition, Sola Scriptura is often used as a rallying cry, but in fact various strands of tradition are still brought to bear upon Biblical interpretation by Protestants.  No one can or should interpret the Bible in isolation, but should instead look to the Church for guidance.  Protestants refer to this “guidance” in terms of confessional documents, while Catholics refer to it as “Sacred Tradition.”  Both, however, have a similar practical effect of constraining interpretation and guiding believers as to what is considered good exegesis versus bad eisegesis and what is considered true versus false.  The point of departure, then, is on what to base this rule of faith: confessional documents or Sacred Tradition?




(Image: The twelve Apostles receiving inspiration from the Holy Spirit and composing the Creed, from Somme le Roy, a moral compendium; By Laurent –, Public Domain,

Aaron Simms is a writer specializing in Christian theology, history, and classical studies.  He is  a member of the American Academy of Religion, the founder of St. Polycarp Publishing House, and a front page contributor for The Resurgent.

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