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13 And it shall come to pass that the Jews shall have the words of the Nephites, and the Nephites shall have the words of the Jews; and the Nephites and the Jews shall have the words of the lost tribes of Israel; and the lost tribes of Israel shall have the words of the Nephites and the Jews.
14 And it shall come to pass that my people, which are of the house of Israel, shall be gathered home unto the lands of their possessions; and my word also shall be gathered in cone. And I will show unto them that fight against my word and against my people, who are of the house of Israel, that I am God, and that I covenanted with Abraham that I would remember his seed forever.
(2 Nephi 29)
Sorry, I must have missed this excellent question! The answer is “No, I would not fail to have faith in Isaiah if the Dead Sea scroll containing the entire book was not found.”
However, I *would *find reason to doubt if the Book of Isaiah contained no predictions of the future that were fulfilled. There are two reasons for this:
1. The predictions of Christ’s life, birth and death are certain proof that God spoke to Isaiah, for Isaiah could never know what he wrote about our Lord and Savior:
5But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed.
6All we like sheep have gone astray; we have turned every one to his own way; and the LORD hath laid on him the iniquity of us all.
(Isaiah 53:5-6)
As the Ethiopian asked Philip in Acts, chapter 8, “Is the prophet speaking of himself, or of another?” Isaiah was, as you and I know, speaking of Christ. But how could the prophet know anything about the man who would be born hundreds of years after he himself was in the grave?
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2. God indicates that He is a God who predicts the future, and all false gods cannot predict the future with the same accuracy and proliferation:
3The voice of him that crieth in the wilderness, Prepare ye the way of the LORD, make straight in the desert a highway for our God.
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21 “ Present your case,” says the LORD.
“ Bring forth your strong reasons,” says the King of Jacob.
22 “ Let them bring forth and show us what will happen;
Let them show the former things, what they were,
That we may consider them,
And know the latter end of them;
Or declare to us things to come.
23 Show the things that are to come hereafter,
That we may know that you are gods;
Yes, do good or do evil,
That we may be dismayed and see it together.
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8"I am the LORD: that is my name: and my glory will I not give to another, neither my praise to graven images.
9Behold, the former things are come to pass, and new things do I declare: before they spring forth I tell you of them."
(Isaiah 40-42)
Our Lord, then, sets Himself apart from false gods by saying He alone will predict the future. This is one reason I’m asking you to provide predictions of the future from the Book of Mormon, and am grateful to have them to consider.
Now, having answered your question first, will you answer mine? If the answer is that there are no extant MSS of the writings of the Nephite prophets, then will you care to further discuss prophecies of the Book of Mormon?