Shorter answer
Besides the King James Version of the Bible, Mormonism accepts three other scriptures as authoritative: the Book of Mormon, the Doctrine and Covenants, and the Pearl of Great Price. For many Christians, quoting this verse to the Mormon missionary is their answer why these other three scriptures do not belong to what is called the “canon” of scripture, which are the 66 authoritative books in the Bible. However, this verse is only referring to the single book of Revelation and not the whole Bible, so using it to support this idea is the same as cheating. Instead of referencing Rev 22:18 to make an out-of-context error, we need to explain how these other Mormon scriptures twist the basic teachings of the Bible and are therefore not authoritative for the Christian. Standing firm to this principle should be reason enough to reject any other added book or scripture.
Longer Answer
“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.”
Many Christians wonder if this passage speaks directly to the extra biblical books of Mormonism, specifically the Book of Mormon. In our opinion it does not. The context of verse 18 seems to speak directly to the book of Revelation, the last book of the Bible written by the apostle John while he was in exile on the island of Patmos.
In the November 20, 1999 issue of the LDS Church News (p.14), an article titled “Warning applies to the book of Revelation” quotes LDS president Howard Hunter, who, while serving as an apostle for the LDS Church, responded to this query by saying, “A careful reading of the words makes it clear that the warning against adding or taking away does not refer to the whole Bible or even to the New Testament, but to use John’s words, on the words of the ‘book of this prophecy.’ That is, the prophecy contained in the book of Revelation.”
We would agree. Still, confining this warning to just the book of Revelation does not get Joseph Smith off the hook entirely. Actually, the Bible contains other warnings regarding those who would attempt to put words in God’s mouth. These include Deuteronomy 4:2; “Ye shall not add unto the word which I command you, neither shall ye diminish ought from it, that ye may keep the commandments of the LORD your God which I command you.” And Proverbs 30:6 states “Add thou not unto his words, lest he reprove thee, and thou be found a liar.”
If both passages were strictly speaking to the problem of adding scripture to the canon, it could be argued that nothing should have been written (or accepted) after Moses penned Deuteronomy since it contains the first of such admonitions. In both cases these passages address the temptation for anyone to presumptuously speak for God. God does not take lightly those who would pretend to speak for Him when they were not authorized to do so. In fact, to be found guilty of speaking for God when God did not speak warranted the death penalty according to Deuteronomy 18:20, “But the prophet, which shall presume to speak a word in my name, which I have not commanded him to speak, or that shall speak in the name of other gods, even that prophet shall die.”
The real issue lies in whether or not Joseph Smith was really acting as a mouthpiece for the Almighty. Did he truly reflect the mind and will of God by his teachings? Or did he inject his own views into what is today referred to as the “restored gospel”? Since it is obvious that his teachings conflict in many respects with those of the Bible, we must choose the latter.
Also consider:
“The final contribution of the Prophet to our understanding of the Apocalypse is in the actual work he did on the text of Revelation as part of his inspired translation of the Bible. As was noted above, he deleted from, added to or changed a total of ninety verses. Obviously, not every one of those changes are of equal significance. The committee that worked on the LDS edition of the King James Version included changes for only forty-seven of the ninety verses, or just slightly better than half of the total changes.” (Gerald N. Lund, Nyman and Millet, ed., The Joseph Smith Translation: The Restoration of Plain and Precious Things, BYU, p.258).
For a Viewpoint on Mormonism show on this topic, go here. You may also view a video about it here.
For other passages discussing common passages used by Latter-day Saints, click here.