Christ and covenants

I just understood better why Isaiah is quoted so much in the Book of Mormon. The title page explains the whole purpose of the Book of Mormon

Which is to show unto the remnant of the house of Israel what great things the Lord hath done for their fathers; and that they may know the covenants of the Lord, that they are not cast off forever—And also to the convincing of the Jew and Gentile that Jesus is the Christ, the Eternal God, manifesting himself unto all nations

Christ and covenants, that's what it's all about. But the more I read Isaiah, the more I realize that this quote from the title page summarizes his writings perfectly. This is the theme all throughout the Book of Isaiah. Sometimes it's buried in a lot of symbolism that might be interpreted on different levels, especially his message of Christ. But a good indicator of how to best summarize Isaiah's message is what Book of Mormon authors say when they comment after having quoted Isaiah. It is always about this theme, no exceptions.

1 Nephi 20-21: Nephi reads Isaiah 48-49 and comments in 1 Nephi 22. He explains how the Jews will harden their hearts against the Holy One of Israel and be scattered, how the Lord will do a marvelous work among the Gentiles, that they will be an instrument in gathering the House of Israel, and that the "Lord God will make bare his arm" in the latter days and bring about the covenants and his gospel to the House of Israel, who shall know that the Lord is their Savior.

2 Nephi 6: Jacob starts reading the end of Isaiah 49 and comments in the same chapter. What he says is very similar to what Nephi says in 1 Nephi 22. (Details here)

2 Nephi 7-8: Jacob quotes Isaiah 50-52:2. His speech continues into chapters 9-10. This is how he starts his comments

1 And now, my beloved brethren, I have read these things that ye might know concerning the covenants of the Lord that he has covenanted with all the house of Israel—

2 That he has spoken unto the Jews, by the mouth of his holy prophets, even from the beginning down, from generation to generation, until the time comes that they shall be restored to the true church and fold of God; when they shall be gathered home to the lands of their inheritance, and shall be established in all their lands of promise. (2 Nephi 9)

Then he goes on to talk about the Savior and the atonement before returning to the topic of covenants and the gathering of Israel in the latter part of 2 Nephi 10.

2 Nephi 12-24: Nephi quotes Isaiah 2-14. Then he spends the next 6 chapters talking about the atonement through Christ and the marvelous work and wonder in the latter-days (while quoting some more Isaiah in between).

Mosiah 14: Abinadi quotes Isaiah 53. Then he spends the next two chapters talking about the salvation through Christ.

3 Nephi 16, 20-22: The Savior himself quotes several parts of Isaiah, Isaiah 54 among them. His own comments in these chapters focus on God's covenants with his children and the gathering of Israel. Language like we find in 3 Nephi 21:4 is repeated a lot

that the covenant of the Father may be fulfilled which he hath covenanted with his people, O house of Israel

I have previously tried to summarize these teachings here.

The Book of Mormon authors are true to its purpose, even when they don't quote Isaiah. But since Isaiah's prophecies are so very well aligned with the purpose of the Book of Mormon, he is used quite a lot as a "second witness" to what the Book of Mormon prophets are testifying of.