Samoans are nearly 100% Christian, belonging to a variety of sects, including congregationalist, Methodist, Catholic, Pentecostal, Mormon, Jehovah's Witnesses, Seventh-day Adventist, and so forth. And as far as I understand these differing parties, they all explain the Bible very differently.
Yet interestingly, despite the lack of unity in scriptural interpretation among the many denominations in Samoa, all but the Mormons (whom I was representing) were unified in their belief that John's conclusion to his Revelation precludes any additional scripture apart from the Bible.
Never mind that Moses said practically the same thing way back in Deuteronomy. Never mind that the Bible as a whole didn't exist in John's, let alone Moses', day. Never mind that the order of the books in the Bible is quite arbitrary. Never mind that John presumably added his Gospel testimony after writing his injunction against adding to the scriptures. The unified consensus among Samoan Christians was that the Bible was all the word that God would give to His people for all time, and that we don't need any more so-called scripture.
Quite frankly, the idea that the Bible contains all of God's word receives no actual support in the Bible itself. In fact, the Bible leaves ample room for additional scripture, not to mention the prophets and apostles who produce it under heaven's inspiration.
For the sake of brevity, I'll just share one verse that I'll call the "leave room for additional scripture" clause:
And other sheep I have, which are not of this fold: them also I must bring, and they shall hear my voice; and there shall be one fold, and one shepherd. (John 10:16)
In a mere 31 words, Jesus says a lot. I'll focus on just two ideas: first, that not all of Jesus' sheep were located at Palestine in which His mortal ministry was confined; second, Jesus' other sheep would hear His voice.
A terrible idea has snuck into post-New Testament Christianity that most of God's children will be damned for eternity, suffering eternal hellfire for not accepting Jesus, when the vast majority of God's children throughout the history of the world never even receive the opportunity to hear of such a being as Jesus.
Following this logic, were it not for the written word, which allows for the wide transmission of "not only the deeds but also the very thoughts of [humankind] through unlimited expanses of space and time," a woefully small number of Old World Christians would be all who could claim salvation through Christ Jesus.
I've played the game telephone, where the original message is greatly distorted by the time it reaches the last person in line, and if we had to rely wholly on an oral transmission of the gospel of Christ--arguably the most important message of all time--imagine what the final result would be after nearly two-thousand years' worth of distortion!
Jesus Himself wrote no scripture; instead, we rely on the testimonies of certain of Jesus' Old World sheep, the evangelists and Peter, Paul, James, and others, to tell us of the deeds and teachings of Jesus--all of whom committed to writing their testimonies of what they saw and heard.
This leads me to the second point, that Jesus' other sheep--who did not live in the land of His mortal ministry--would hear His voice. If they heard His voice, does it not stand to reason that they would commit His sayings to writing? And isn't it at least as possible that we might learn about those sayings someday, in a manner at least as marvelous as the coming forth of the Dead Sea scrolls, which had been hidden up for many years, just waiting to be found?
Enter the Book of Mormon.
The Book of Mormon is the voice of the Good Shepherd to others of His sheep living in the New World. It was given to be another testament of Jesus Christ, a second witness for the purpose of "convincing the Jew and the Gentile that Jesus is the Christ, the Eternal God, manifesting himself unto all nations. It is a witness that truly God is no respecter of persons, that His words never cease, and that He is the same yesterday, today, and forever.
Above all things, the Book of Mormon is manifestly a Christian document, produced by ancient Christians, who by the spirit of prophecy and revelation produced a work that benefits us today by drawing us closer to God and Christ. It was brought forth in our day by the gift and power of God.
My message to the Samoan Christians during my mission was that any Christian who prayerfully studies the Book of Mormon in addition to the Bible will find his or her faith in Jesus strengthened in ways he or she never thought possible. This has been my experience with the Bible and the Book of Mormon and indeed all holy writ.