Is the Book of Mormon and addition to the Bible?

No, it is not. Many times we see this argument made based on scriptures found in the Book of Revelation.

1. Rev. 22: 18
   18 For I testify unto every man that heareth the words of the prophecy of this book, If any man shall ^aadd unto these things, God shall add unto him the ^bplagues that are written in this book: (http://scriptures.lds.org/en/search?type=references&last=Rev.+22&help=&ro=checked&search =Rev.+22%3A18%0D%0A&do=Search&show=%0D%0A%0D%0A)

I believe that this scripture is true. I believe that no man can endeavor to add to or take away from the word of God through his own decision. This would desecrate the scriptural text. I will make my argument using two approaches. 1. God calls good men to act as prophets, and these prophets receive revelation from God and write it down. This is the source of scripture. 2. There are other places where God commanded men to not add to his word, he did not only do so in the last chapter of the New Testament.

1. According to Christians, God is unchanging. He is the same from eternity to eternity. Mormons (or members of the Church of Jesus Christ of Latter-day Saints) take this literally. We truly believe that God does not change. He has a pattern by which he teaches his children on earth. He calls a prophet, reveals truth to this prophet, and the prophet teaches the truth to the people. We believe that God has not stopped this process. Given that he is constant and unchanging, he still calls prophets today who receive revelation and write it down.

The Book of Mormon is the ancient record of prophets that lived in the Americas (http://mormon.org/mormonorg/eng/basic-beliefs/the-restoration-of-truth/the-book-of-mormon). This book was written in the same way the Bible was written. God gave revelation to prophets, and these prophets wrote down what God gave to them. It is not an addition to the Bible, but another testament of Christ that does the same thing as the Bible: testify of Christ.

In modern times, God called another prophet, and commanded him to translate this ancient record in to English. This prophet was Joseph Smith (http://mormon.org/mormonorg/eng/basic-beliefs/the-restoration-of-truth/the-restoration-of-the-gospel). Just as in ancient times, God called Joseph as a prophet to do His work on earth. Joseph translated the Book of Mormon, and also received other revelations. These he wrote down, just as prophets have always done since the beginning of time (http://scriptures.lds.org/en/dc/contents). Thus we see that men can't add to God's word, but God can. It is his word, he can do whatever he pleases with His own word. The Bible does not put constraints on God, rather it is a glimpse into the works of the Almighty. To say that God has changed and no longer reveals his word to prophets, or to say that God cannot add to his own word by way of continued revelation is false doctrine.

2. Many of those who use Revelations 22:18 as an argument against God revealing any further scripture take the verse to mean that any scripture revealed after that particular statement would be invalid. To take this position in a literaly, we might then say that verses 19-21 of the same chapter can have no place in the Bible, given that they were added on after this verse was written.

This argument seems silly. Let us look at a more extreme case. Buried in the Old Testament we find this interesting verse:

1. Deut. 4: 2
   2 Ye shall not ^aadd 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. (http://scriptures.lds.org/en/search?type=words&last=Deut+%3A2&help=&wo=checked& search=Deut+4%3A2&do=Search&iw=scriptures&tx=checked&af=checked&hw=checked&sw=checked
   

If we apply the same logic as we applied with the Rev. 22:18 argument, we must reject any scripture that follows this verse as well. This means that we must reject the majority of the Old Testament, and the entire New Testament. According to this argument, what follows this verse cannot be God's word because it was "added" to scripture after God had explicitly commanded that the people not add to his word.

As far as I understand, the New Testament as we have it today is the compilation of many of the letters and writings of the Apostles. It was written down on many different scrolls, and copied several times over the centuries. It wasn't until hundreds of years after the resurrection of Christ and after much of the Christian persecutions that the writings that had survived were put together into a book form. This would support the fact that John was indicating that no man should add to the specific revelation that he was receiving at the time, given that the New Testament was compiled years after he had received this revelation on the Isle of Potmos. This argument intrigues me, and I intend to do more research on the subject.

Then why do we have more scripture? Again... because God calls prophets and reveals his will to them, and hey obey. They write down what he tells them to write down. God is unchanging and constant. The Book of Mormon is not a man made addition to the Bible, rather it is evidence that God continues to reveal his word to prophets, just as he did after Deut. 4:2, and just as he always will.