Every now and then you'll hear some denominational preacher claim that he has received a revelation from God of some new truth. Charles Taze Russell and Judge Rutherford, both prominent in the early history of Jehovah's Witness, made such claims. Joseph Smith claimed to have been led by an angel to dig up some plates out of a hill. He then allegedly translated the message on those plates and gave the world the "new truth" contained in the Book of Mormon. Just about every major cult claims special revelations from God. The vast majority of charismatic groups also regularly boast of the latest thing God has allegedly told them.
Several passages of Scripture mitigate against these claims and demonstrate their absurdity. Shortly before his death, Jesus said unto his disciples, "I have yet many things to say unto you, but ye cannot bear them now. Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will show you things to come" (John 16:12-13). This passage designates the apostles as the divinely appointed receptacles of all truth. It is not possible to overemphasize the significance of the word "all" in verse 13. Since Jesus promised to reveal all truth to his apostles, that leaves not one particle of truth to be revealed to anyone else. If any truth needs to be revealed today, then the apostles didn't receive what Jesus promised. By the time the last apostle died, all truth must have been revealed or else Jesus would be found guilty of lying.
I'm reminded of the story of a man who was spending the night at someone's home. The next morning, at breakfast, the woman of the house told her guest that God had told her something personally the night before. The guest replied, "Well, God told me that he didn't tell you that." She looked at him with a startled expression and waited for his explanation. He proceeded to show her John 16:12-13 and said, "This is where God told me that he didn't tell you what you allege."
God has given us all things that pertain to life and godliness (2 Peter 1:3). The faith has once for all been delivered (Jude 3). Paul wrote, “All Scripture is inspired of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness: that the man of God may be perfect, thoroughly furnished unto all good works” (2 Tim. 3:16-17). God gave us a book which completely furnishes the child of God with the information needed to be pleasing in God's sight.
Those who assert that they are receiving modern-day revelations ought to confirm their words with signs following as the apostles did in the first century (Mark 16:20; Heb. 2:3-4). Paul told the Thessalonians, “For our gospel came not unto you in word only, but also in power, and in the Holy Spirit, and in much assurance” (1 Thess. 1:5). The so-called revelations received by men today come to us in word only and not in demonstration of the Spirit's power. Why doesn't the Holy Spirit confirm the authenticity of the message of these preachers as he did on the day of Pentecost in Acts 2? The answer is that the miracles of the first century have vanished away as Paul said they would when the perfect law of liberty, God's written revelation was completed (1 Cor. 13:8-13; Eph. 4:8-16). The plain fact of the matter is that the only signs we need today are those recorded in Scripture for the purpose of producing faith in Christ (John 20:30-31). All truth has been revealed!