Prophecy and the Closed Canon (Part 2) By John MacArthur

How the Biblical Canon Was Chosen and Closed
Jude 3 is a crucial passage on the completeness of our Bibles. This statement, penned by Jude before the New Testament was complete, nevertheless looked forward to the completion of the entire canon:
Beloved, while I was making every effort to write to you about our common salvation, I felt the necessity to write to you appealing that you contend earnestly for the faith which was once for all delivered to the saints. (Jude 3)
In the Greek text the definite article preceding “faith” points to the one and only faith: “the faith.” There is no other. Such passages as Galatians 1:23 (“He who once persecuted us is now preaching the faith”) and 1 Timothy 4:1 (“In latter times some will fall away from the faith”) indicate this objective use of the expression “the faith” was common in apostolic times. Greek scholar Henry Alford wrote that the faith is “objective here: the sum of that which Christians believe” (Alford’s Greek Testament, 4:530).
Note also the crucial phrase “once for all” in Jude 3. The Greek word here is hapax, which refers to something done for all time, with lasting results, never needing repetition. Nothing needs to be added to the faith that has been delivered “once for all.”
George Lawlor, who has written an excellent work on Jude, made the following comment:
The Christian faith is unchangeable, which is not to say that men and women of every generation do not need to find it, experience it, and live it; but it does mean that every new doctrine that arises, even though its legitimacy may be plausibly asserted, is a false doctrine. All claims to convey some additional revelation to that which has been given by God in this body of truth are false claims and must be rejected. (Jude, 45).
Also important in Jude 3 is the word “delivered.” In the Greek it is an aorist passive participle, which in this context indicates an act completed in the past with no continuing element. In this instance the passive voice means the faith was not discovered by men, but given to men by God. How did He do that? Through His Word—the Bible.
And so through the Scriptures God has given us a body of teaching that is final and complete. Our Christian faith rests on historical, objective revelation. That rules out all inspired prophecies, seers, and other forms of new revelation until God speaks again at the return of Christ (cf. Acts 2:16–21; Rev. 11:1–13).
In the meantime, Scripture warns us to be wary of false prophets. Jesus said that in our age “false christs and false prophets will show great signs and wonders, so as to mislead, if possible, even the elect” (Matt. 24:24). Signs and wonders alone are no proof that a person speaks for God. John wrote, “Beloved, do not believe every spirit, but test the spirits to see whether they are from God; because many false prophets have gone out into the world” (1 John 4:1).
Ultimately, Scripture is the test of everything; it is the Christian’s standard. In fact, the word canon means “a rule, standard, or measuring rod.” The canon of Scripture is the measuring rod of the Christian faith, and it is complete.