Revelation 22:18 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:
Denunciations against those who add to or take from the Scriptures (The New Topical Textbook, subheading under the major heading, “The Scriptures,” page 240).
It seems fitting that at the close of the New Testament this warning against adding to the Scripture should be issued. There are some who argue this prohibition applies only to the book of Revelation. I think otherwise. I believe God providentially arranged this warning’s placement at the close of the New Testament to warn against adding to the now closed canon of Scripture. John was the last writer to pen a New Testament book. John outlived the other writers of the New Testament by as many as 30 years. It is highly likely, though it cannot strictly be proven historically with the evidence in our possession, that John himself finalized and closed the New Testament canon or list of books to be contained in the New Testament. Such is the position argued or presented in an appendix at the end of Townsend’s Analysis, a most helpful arrangement of Scripture in chronological order produced in the nineteenth century. In any case, I agree with his position, or his prejudices, however you may see it!
I think the warning applies to any person or group that would add to the Bible as we have it in its 66 books, 39 in the Old Testament and 27 in the New Testament, additional revelation or Tradition that is regarded as divinely inspired or authoritative on a par with Scripture itself.
There are and have been certain religious groups who claim to have additional books that belong in the Bible or new books of revelatory material which they believe to be specially, even divinely inspired. The Mormons have their Book of Mormon. The Roman Catholics have added a number of apocryphal books to the Old Testament, books present in the Septuagint but not accepted by the Jews in Israel and not named as Scripture by the New Testament writers. The Roman Catholics have also added Tradition into the mix as authoritative, to be considered along side the Bible in formulating doctrine. Other groups have their inspired prophetess (like Seventh-day Adventists and Ellen G. White, or the Christian Science church with Mary Baker Eddy). Other groups claim to be the only source of authoritative Bible teaching, or similarly make the claim to be the one true church. All of these are in danger of violating the command in Revelation 22:18 not to add to God’s Word, the Bible.
I think the best choice is to go by the Bible alone and in its entirety, and seek to have fellowship with others who have the proper regard for the Bible.
For those who desire to DIG DEEPER into this subject:
(1) Consult the cross references given in Nelson’s Cross Reference Guide to the Bible on page 1521 for Revelation 22:18.
(2) Consult the cross references given in The New Treasury of Scripture Knowledge on page 1538 or in Logos 5 Bible software for Revelation 22:18.
(3) Lacking access to those two resources, consult the cross references for this passage as I have developed them as given below:
Revelation 22:18. testify. See on ver. Re 22:16. *Re 3:14. Ep 4:17. 1 Th 4:6. heareth. See on Re 1:3. this book. ver. Re 22:7, 9. Dt 31:24. +Ac 1:20. If. FS184C, +Mt 4:9. add unto these. >Dt 4:2. >Dt 12:32. Jsh 1:7. 1 S 12:19. 1 K 12:11. Pr 19:27. +*Pr 30:6. +**Is 8:20. **Je 23:28, 29. Mt 7:15-20. **Mt 15:6-9, 13. 24:11, 24. 28:20. 1 Cor 3:12, 13. God shall add. T#1108. Re 14:10, 11. 15:1. Re 16:1-3, 8-11, 17, 18, 21. 19:20. 20:10, 15. **Le 26:18, 24, 25, 28, 37. %Pr 10:22. the plagues. >Dt 29:20.