Isaiah’s writings focus on Isaiah's own personal testimony that "Jesus Christ is the only true source of hope for men and women living in a fallen world". Consequently, Nephi's writings on his personal records contain hundreds of verses that Isaiah wrote that testify of the Savior. One scholar noted that “of the 425 separate verses of Isaiah which are quoted in the Book of Mormon, 391 say something about the attributes or mission of Jesus Christ” (Monte S.Nyman, “Great Are the Words of Isaiah” [1980], 7).

Similarly, Nephi recognized that Isaiah’s testimony was very similar to his own personal testimony. Both had seen the Lord. Nephi even says this in 2 Nephi 11:2-3: (br)“And now I, Nephi, write more of the words of Isaiah, for my soul delighteth in his words. For I will liken his words unto my people, and I will send them forth unto all my children, for he verily saw my Redeemer, even as I have seen him. And my brother, Jacob, also has seen him as I have seen him; wherefore, I will send their words forth unto my children to prove unto them that my words are true. Wherefore, by the words of three, God hath said, I will establish my word. Nevertheless, God sendeth more witnesses, and he proveth all his words."

He then continues in 2 Nephi 11 verse 4 with this: "Behold, my soul delighteth in proving unto my people the truth of the coming of Christ; for, for this end hath the law of Moses been given; and all things which have been given of God from the beginning of the world, unto man, are the typifying of him."

By these facts and scripture verses we can decipher that Nephi's sole intent was to teach his people about Jesus Christ and the significance of following him and his teachings - even though Christ has not been born yet. And Nephi emphasized this point by quoting from many of Isaiah's teachings which were essentially saying the same thing. Jesus Christ was the Messiah that was to be sent to save the world from itself - from all of it's immorality, wickedness, moral decay and inequities. Isaiah preached this and so did Nephi. And he used Isaiah's writings to emphasize this point.

Isaiah's has many references for Jesus Christ but his main one was "The Prince of Peace and to reign on David's Throne" (see Isaiah 9:6-7). At the time of Isaiah, the people of Israel has been told of a Messiah to come from many of the prophets, and Jesus Christ was that Messiah. Nephi also saw this and prophesied this. That is the main reason why he uses (includes) Isaiah's writings in his records.