Since the reliability of the NT is constantly attacked (due to its main theme: Jesus as the only means of salvation), Christians should be aware of the nature and formation of the NT. Thus, the following is a concise summation of this important topic. First, it must be understood that the erroneous notion that the first-century church was without a functioning NT canon because no formal ecclesiastical (church) pronouncement was made, is historically untrue. Note the following:
In 2 Peter 3:15-16, Peter establishes the letters of Paul as graphē, “Scripture.” This confirms that Paul’s epistles (most of them) were circulating (probably as a set) before the death of Peter around A.D. 64-66. In 1 Timothy 5:18, Paul establishes the book of Luke (10:7) also as graphē, “Scripture.” Note that here both Deuteronomy 25:4 and Luke 10:7 are preceded by the phrase, legei gar hē graphē, “For Scripture says.” Further, in reference to the Apostle Peter, Jude remembers what “was spoken beforehand by the apostles” (v. 17). Then, in verse 18, Jude quotes from Peter (cf. 2 Pet. 3:3). The contextual correspondence between 2 Peter 2:1ff. and Jude 6ff. unquestionably substantiates that either Jude quoted from Peter or the converse showing that these books were also circulated, collected, and read by Christians in the first century.
As the NT record shows, immediately after the NT letters were written, they were collected (cf. Rev. 1:11), circulated (cf. Col. 4:16; 2 Pet. 3:15-16), and read (cf. 1 Thess. 5:27; Rev. 1:3) in the original churches. Hence, the first century church enjoyed and recognized the apostolic teachings contained in the letters of the original apostles. They indeed had a functioning canon that was sufficient for the proclamation of truth.
Since the NT church was “built on the foundation of the apostles and prophets” (Eph. 2:20) the chief test or norm of canonicity was “apostolicity.” That is, each book of the NT has either apostolic authorship or apostolic teaching. Canonization starts with the identification of what was theopneustos, “God breathed out” (2 Tim. 3:16).
First, there were several reasons as to why the early church progressively collected and codified (i.e., canonized) the NT books:
1) Books were prophetic,
2) Demands of the early church: Because they contained the words and actions of Jesus Christ and the apostolic teachings, these books provided theological and ethical instructions, edification, and encouragement for the church “so that the man of God may be adequate, equipped for every good work” (2 Tim. 3:17). Thus, it was necessary to have a full collection of the NT books that could provide the authoritative norm for faith and practice,
3) Heretical challenges: When heresies began to surface, the church quickly and sharply refuted them by way of ecclesiastical (i.e., church) councils and definitive creeds. When the writings of apostles were purposely misrepresented and/or forged (e.g., the Gospel of Thomas, Judas, etc.), the church found it necessary to establish what belonged in the canon,
4) Missionary purposes: Because of the rapid spread of Christianity throughout other countries, there was a need to translate the Bible into other languages, and
5) Persecution: In times of persecution, it was important for church officials to preserve authoritative (canonical) books which might be handed over to the police and be destroyed.
Determining Canon Criteria
It is incorrect to assert that the church created the canon, for the church did not create the canon, but rather she discovered what was already recognized. As seen, immediately after NT books were written, they were collected, circulated, quoted, and read in the original churches. It was this process of canonization that shaped the post-apostolic church’s idea of canonization. The basis of canonicity, then, was inspiration: “God breathed out.” The NT authors wrote as God the Holy Spirit moved them. Hence, the instrument of canonicity in which God employed was the apostles—or those with apostolic authority: The absolute canonical test, then, was apostolicity. The central principles utilized by the church to determine canonicity were as follows:
1. APOSTOLICITY: Since the NT church was (aorist participle). “built on the foundation of the apostles and prophets” (Eph. 2:20), the indispensable test for NT canonicity was apostolicity. Thus, every NT book was written by a “foundational” apostle (or one with apostolic authority). Ignatius, bishop of Antioch (c. A.D. 107) says: “I do not give you orders like Peter and Paul. They were apostles: I am [not]” (Rom. 4:3).
2. ANTIQUITY: Simply, if a writing was the work of an apostle (or an authoritative associate), it had to belong to the apostolic age. Writings after this could not be apostolic, and hence canonical. For example, even though the highly regarded Shepherd of Hermas (c. A.D. 120) was found in the Muratorian Fragment and some early codices, its late date of composition, precluded it from canonical status. Furthermore, most of the pseudepigrapha (i.e., “false writings”) were rejected for that reason.
3. ORTHODOXY: Genuine apostolic writings would be doctrinally consistent (i.e., orthodox) with the apostolic faith (regula fidei). For example, the so-called Gospel of Peter and Thomas are filled with silly stories and Gnostic teachings, which the apostles (and the early church) sharply refuted (e.g., Col., and 1 and 2 John were written specifically against the Gnostic heresy).
4. CATHOLICITY: The universal church collectively recognized genuine apostolic writings. If a book had only local recognition, it was not likely to be accepted as canonical. Naturally, the NT books that were first collected, circulated, quoted, and read by the original churches became universally recognized.
5. TRADITIONAL USE: Similar to the principle of Catholicity, books that were collected, circulated, quoted, and read by the original churches were, of course, well known among the churches. This criterion examines the church’s habitual (i.e., traditional) use of writings. It inquires as to what NT books were accepted as apostolic. For example, prior to Nicea (A.D. 325), the NT quotations from early church Fathers were so abundant that almost the entire NT could be restructured, based on these writings. The books of the NT were traditionally treated as Scripture. If a church leader in the third or fourth century submitted a book claiming its apostolicity and it was previously unknown, he would have great difficulty in gaining acceptance for it.
6. INSPIRATION: The church believed that only books that were theopneustos, “God breathed out,” were canonical. Thus, inspiration was the means by which the revelation of God was brought to the written record. The vocabulary belonged to the NT authors, but the message was God’s. “Paul wrote,” says Clement of Rome (c. A.D. 90), “with true inspiration” (Corinthians, 47.3). Inspiration, therefore, was a criterion of verification as to what books were apostolic and hence, canonical.
Categorizing the Canon
The early church Father, Origen, first grappled with the problem of the church not having an “official demarcation” between canonical and non-canonical books. Then, about a century later, the church historian Eusebius defined and modified Origen’s classification in the following four categories:
Homologoumena (“to speak the same,” i.e., books that were accepted by all): The Four Gospels, Acts, the Epistles of Paul, 1 Peter, and 1 John, and Revelation (although he went back and forth as to the category of Rev).
Antilegomena (“spoken against,” i.e., books that were disputed by some): James, 2 Peter, 2 and 3 John, Jude, and Revelation.
Notha (“spurious” or apocrypha, i.e., books that were accepted by some): The alleged Epistle of Barnabas (c. A.D. 70); Clement’s first Epistle to the Corinthians (c. A.D. 96); Teaching of the Apostles (i.e., Didache, A.D. 100-120); Hermas’s The Shepherd (c. A.D. 120); Polycarp’s Epistle to the Philippians (c. A.D. 110); etc.
Pseudepigrapha: (“false writings,” i.e., books that were disputed/rejected by all): “Writings published by heretics,” Eusebius declares, “under the names of the apostles, such books as the Gospels of Peter, of Thomas, Matthias, Judas, etc. or the Acts of Andrew, John, etc. The point here is that no early church Father ever accepted them; they saw them as “false writings,” for most of these books were written by Gnostics.
The Earliest Lists
During the next two centuries, the controversy and doubts over the antilegomena books gradually faded away and there was a final and official recognition of all twenty-seven books of the NT by the universal church. Aside from the early partial NT lists of books, the first known writer to list all twenty-seven books of the NT was Athanasius in his 39th Easter Letter (A.D. 367). Later, in A.D. 393, the twenty-seven books of the NT were laid down as canonical at the regional Council of Hippo under Augustine’s See. Then, four years later, at the third Council of Carthage, the twenty-seven books of the NT were reaffirmed as belonging to the canon. Thus, these twenty-seven books that were universally confirmed at these councils, agree with the present-day canon of the NT that we have in our hands.
What is paramount in accurately understanding NT canonicity is that at these official councils, the early church did not invent or create the NT canon nor did they accept or reject books based on “church authority,” but rather, at these councils, the early church codified and confirmed what was already recognized and established by the people of God starting in the first century (as seen above).
The Canon is closed
So then you are no longer strangers and aliens, but you are fellow citizens with the saints, and are of God’s household having been built on the foundation of the apostles and prophets, Christ Jesus Himself being the corner stone (Eph. 2:19-20).
The foundation of the NT was laid once and for all. It was built on the apostle and prophets. The text does not say that the church was built on Christ, but rather on the apostles and prophets. Jesus Christ is the cornerstone that holds the whole church together. Paul does not envisage a succession of new apostles (as Rome teaches today). This is clear due to the fact that Paul uses the aorist passive participle form of epoikodomeō of (epoikodomēthentes, lit., “having been built”). Hence, the action of the verb indicates that the foundation that was laid once and thus never needs to be repeated.
The notion of ‘successive apostles’ as taught by groups such as Roman Catholics and LDS do not consider (a) logically, if there is a need for new foundational apostles, then, the foundation was never really laid to begin with. Hence, something foundational by definition never needs additional foundations, and (b) the idea that we need new apostles or even secondary ones who will add to the fundamental work of the first century are really implying that we need new foundations in addition to or regardless of the foundation that was already laid: viz. the NT “apostles and prophets.” Thus, each new foundation would logically require a new cornerstone.
In direct contrast to the Protestant concept of sola Scriptura (“Scripture alone”) is sola Ecclesia (i.e., “Church alone”), which is clearly the marrow of groups such as Catholicism. Hence, it is not that the Catholic apologist does not have the ability to exegete, but he has no need, for the Church has done the job for him. For the Catholic sees his Church, not Scripture, as the final sole authority in all areas of life and theology (cf. Catechism of the Catholic Church, para. 84-85, 113).
The Canon is closed theologically and historically
1) Theologically (cf. Heb. 1:1): Every NT book was written by an apostle (or one with apostolic authorship). The apostolic age ended with the death of the apostles (cf. Acts 1:22). In Ephesians 2:20, Paul states that the foundation of the church has been built (never to be repeated) by these foundational apostles. Thus, there cannot be any “new revelation” for the church (contrary to what Mormons and Catholics believe), and
2) Historically: There is no historical evidence that any new foundational apostle has ever existed. Virtually every non-Christian cult has a new prophet or apostle(s) carrying new a message, which rejects and/or redefines the Jesus Christ of biblical revelation. Hence, they all have some reason as to why sola scriptura (Scripture alone) does not work.
 The term “canon” refers to a set or list of authoritative biblical books that are regarded as Scripture (i.e., theopneustos, “God breathed out”; 2 Tim. 3:16).
 Colossians 4:16 reads, “When this letter is read among you, have it read in the church of the Laodiceans; and you, for your part read my letter that is coming from Laodicea.” The letter to the Laodiceans to which Paul is referring was probably the letter to the Ephesians for the following reason: 1) Paul does not say that it is a letter to the or of the Laodiceans, but rather ek Laodikeias, “from Laodicea,” 2) Paul wrote Ephesians around the same time as Colossians and sent it to another church in the same area, 3) the earliest MSS of Ephesians lack the phrase en Ephesō, “at Ephesus.” Note that Paul spent three years ministering to the Ephesians (cf. Acts 20:31), thus, it would be quite inconsistent for him not to mention the name of the people (or church) to which he wrote, and 4) there is no historical evidence that a “genuine” letter to the Laodiceans was known.