Continuing a series of posts about Canonicity (how we know which books belong in the bible), the late Greg Bahnsen penned a helpful essay a few years back. View the entire essay here.
In the essay Bahnsen comments on the historic settlement regarding canon-
The Canon Historically Settled Under God's Providence
Those works which God gave to His people for their canon always received immediate recognition as inspired, at least by a portion of the church (e.g., Deut. 31:24-26; Josh. 24:25; I Sam. 10:25; Dan. 9:2; I Cor. 14:37; I Thess. 2:13; 5:27; II Thess. 3:14; II Peter 3:15-16), and God intended for those writings to receive recognition by the church as a whole (e.g., Col. 4:16; Rev. 1:4). The Spiritual discernment of inspired writings from God by the corporate church was, of course, sometimes a drawn-out process and struggle. This is due to the fact that the ancient world had slow means of communication and transportation (thus taking some time for epistles to circulate), coupled with the understandable caution of the church before the threat of false teachers (thus producing dialogue and debate along the way to achieving one mind).
Historical evidence indicates that, even with the difficulties mentioned above, the Old and New Testament canons were substantially recognized and already established in the Christian church by the end of the second century. However, there is adequate Biblical and theological reason to believe that the canon of Scripture was essentially settled even in the earliest days of the church.
By the time of Jesus there existed a well-defined body of covenantal literature which, under the influence of the Old Testament prophets, was recognized as defining and controlling genuine faith. When Jesus or the apostles appealed simply to 'the Scriptures' against their Jewish opponents, there is no suggestion whatsoever that the identity and limits of such writings were vague or in dispute. Confirmation of the contents of the Jewish canon is found toward the end of the first century in the writings of Josephus (the Jewish historian) and among the rabbis of Jamnia.
The New Testament church acknowledged the canonical authority of this Old Testament corpus, noting that '...not one jot or tittle' (Matt. 5:18) of 'the law of Moses, and the prophets, and the psalms' (Luke 24:44) was challenged or repudiated by our Lord. His full submission to that canon was evident from the fact that He declared 'the Scripture cannot be broken' (John 10:35). As Paul later said: 'whatever things were previously written were written for our instruction' (Rom. 15:4).
The traditional Jewish canon was divided into three sections (Law, Prophets, Writings), and an unusual feature of the last section was the listing of Chronicles out of historical order, placing it after Ezra-Nehemiah and making it the last book of the canon. In light of this, the words of Jesus in Luke 11:50-51 reflect the settled character of the Jewish canon (with its peculiar order) already in his day. Christ uses the expression 'from the blood of Abel to the blood of Zechariah,' which appears troublesome since Zechariah was not chronologically the last martyr mentioned in the Bible (cf. Jer. 26:20-23). However, Zechariah is the last martyr we read of in the Old Testament according to Jewish canonical order (cf. II Chron. 24:20-22), which was apparently recognized by Jesus and his hearers.
As for the New Testament, the covenantal words of Christ -- which determine our lives and destinies (e.g., John 5:38-40; 8:31; 12:48-50; 14:15, 23-24) -- have been, through the power of the Holy Spirit, delivered faithfully to us by Christ's apostles: 'But the Comforter, even the Holy Spirit, whom the Father will send in my name, he shall teach you all things, and bring to your remembrance all that I said unto you' (John 14:26; cf. 15:26-27; 14:16-17; 16:13-15).
The very concept of an 'apostle' in Jewish jurisprudence was that of a man who in the name of another could appear with authority and speak for that other man (e.g., 'the apostle for a person is as this person himself,' it was said). Accordingly, Jesus told His apostles, 'He who receives you receives Me, and he who receives Me receives Him who sent me' (Matt. 10:40). And through these apostles He promised to 'build My church' (Matt. 16:18).
We know that in this way there came about a body of New Testament literature which the church, 'being built upon the foundation of the apostles and prophets, Christ Jesus himself being the cornerstone' (Eph. 2:20), came to recognize as God's own word, being the canon of their covenantal relation with Him. This recognition traces from the days of the apostles themselves, who either identified their own works as canonical (e.g., Gal. 1:1, 11-12; I Cor. 14:37), or verified the canonical authority of the works by other apostles (e.g., II Peter 3:16) and writers (e.g., I Tim. 5:18, citing Luke 10:7).
But whether or not each was given particular written attention by an apostle, the individual books of the New Testament came to be seen for what they were: the revelation of Jesus Christ through His chosen messengers. It is in this body of literature that God's people discern the authoritative word of their Lord -- as Jesus said: 'My sheep hear My voice, and they follow Me' (John 10:27).
To recapitulate: we know from God's Word (1) that the church of the New Covenant recognized the standing canon of the Old Testament, and (2) that the Lord intended for the New Covenant church to be built upon the word of the apostles, coming thereby to recognize the canonical literature of the New Testament. To these premises we can add the conviction (3) that all of history is governed by God's providence ('...according to the plan of Him who works all things according to the counsel of His own will,' Eph. 1:11). So then, trusting Christ's promise that He would indeed build His church, and being confident in the controlling sovereignty of God, we can be assured the God-ordained recognition of the canon would be providentially accomplished -- which, in retrospect, is now a matter of historical record.
To think otherwise would be, in actual effect, to deprive the Christian church of the sure word of God. And that would in turn (a) undermine confidence in the gospel, contrary to God's promise and our spiritual necessity, as well as (b) deprive us of the philosophical precondition of any knowledge whatsoever, thus consigning us (in principle) to utter scepticism.