God lovingly commands us in 1 John we are to try the spirits to see if they are of God or of men. He would not command us unless he gave us the tools.
There are two that I am aware of . One to protect the integrity of one word (singular). Seeing change the intended meaning can change the authorship and the direction of the commandments.(many words) The power of one word.
Deuteronomy 4 King James Version (KJV) Now therefore hearken, O Israel, unto the statutes and unto the judgments, which I teach you, for to do them, that ye may live, and go in and possess the land which the Lord God of your fathers giveth you.Ye shall not add unto the word (singular) which I command you, neither shall ye diminish ought from it, that ye may keep the commandments (many words) of the Lord your God which I command you.
Then at the end of any possibility of new revelations of God moving men to record his thoughts that could not add . The final warning do not add to the whole of perfect word called this book. The words of the prophecy
For I testify unto every man that heareth the words of the prophecy of this book, If any man shall add unto these things, God shall add unto him the plagues that are written in this book:And if any man shall take away from the words of the book of this prophecy, God shall take away his part out of the book of life, and out of the holy city, and from the things which are written in this book .Revelation 22: 18_19
Having those two as integrity protectors it becomes the supposed or claim of. . . . Thus says the Lord, I had a dream or vision or heard a auditable voice, had a near death experience or out of the body . We are to believe not. He clearly warns us before hand . Knowing the last prophet to bring a new revelation was John.
Matthew 24:22-24 King James Version (KJV) And except those days should be shortened, there should no flesh be saved: but for the elect's sake those days shall be shortened. Then if any man shall say unto you, Lo, here is Christ, or there; believe it not. For there shall arise false Christs, and false prophets, and shall shew great signs and wonders; insomuch that, if it were possible, they shall deceive the very elect. Behold, I have "told you before." Wherefore if they shall say unto you, Behold, he is in the desert; go not forth: behold, he is in the secret chambers; believe it not.
Therefore making it imposible to decive the elect that abides in the warning.