Mormon says if you believe the Bible, you will believe the Book of Mormon. How is it then that so many Bible lovers have rejected the Book of Mormon? Before we answer that question, let's consider the testimony of Nephi. He declared a similar doctrine: that if you believe in Jesus Christ, you will believe in the Book of Mormon, And if ye shall believe in Christ ye will believe in these words, for they are the words of Christ, and he hath given them unto me (2 Nephi 33:10). Based on these two prophetic statements, everyone who either believes in Christ or believes the Bible will believe the Book of Mormon. Why is it then that the Book of Mormon is summarily dismissed by most of the Christian world?
The answer is because the Christian who believes the Bible but rejects the Book of Mormon doesn't believe in the Bible as much as his preacher's doctrine that there can be no other scripture or revelation. Similarly, the Christian who claims faith in Christ yet rejects the Book of Mormon does not really know the voice of the Master. For if he knew the Master, he would recognize His voice whether it came through the pages of the Bible or the Book of Mormon. Of these, the Lord said, whoso receiveth not my voice is not acquainted with my voice, and is not of me (DC 84:52), for My sheep hear my voice, and I know them, and they follow me (Jn 10:27). Therefore, when a "Christian" rejects the Book of Mormon, it makes no statement about the book, but it makes a big statement about the "Christian."
Bruce R. McConkie
"From these passages we reach certain clear conclusions relative to believing in Christ and in his holy word. Among them are these: A belief in Christ and a belief in the Book of Mormon go together; they are locked in each other's arms; they cannot be separated. Like Ezekiel's two sticks, they are one in the hands of the Father. Those who believe in Christ also believe the Book of Mormon because it contains the words of Christ. Those who believe the words of Christ, as given by his disciples and as recorded in Book of Mormon, believe in Christ. And those who do not believe these words do not believe in him. The Book of Mormon bears witness of Christ and of the Bible; it is written to persuade men to believe in their Lord and in his ancient word. Those who believe the Book of Mormon believe the Bible, and those who believe the Bible believe the Book of Mormon." (The Millenial Messiah, p. 177)
Brigham Young:
"No man can say that this book (laying his hand on the Bible) is true...and at the same time say, that the Book of Mormon is untrue...There is not that person on the face of the earth who has had the privilege of learning the gospel of Jesus Christ from these two books, that can say that one is true, and the other is false. No Latter-day Saint, no man or woman, can say the Book of Mormon is true, and at the same time say that the Bible is untrue. If one be true, both are." (Journal of Discourses, 1:38)