In 1 Nephi 20-21, the prophet Isaiah addresses the house of Israel, emphasizing their disobedience despite their covenant with God. Isaiah condemns them for not living righteously, even though they claim to follow the Lord. God, in His mercy, has refined them through affliction and promises to fulfill His word and redeem His people, urging them to flee from Babylon’s wickedness. Isaiah's writings also include prophecies of the Messiah, the gathering of Israel, and the role of the Gentiles in the latter-day restoration of the gospel. Nephi includes Isaiah’s words to show their relevance to his own people and to testify of Jesus Christ, highlighting the importance of understanding and applying Isaiah's teachings. Isaiah’s prophecies, rich in symbolism and often dualistic, require diligent study and spiritual insight to fully grasp their meaning.

Nephi explains that the people struggled to understand Isaiah because they lacked knowledge of Jewish prophecy, the spirit of prophecy, and understanding of Jewish customs. Modern readers also face challenges due to the poetic form, dualistic prophecies, and extensive symbolism. To comprehend Isaiah, one should study other scriptures, seek the spirit of prophecy, and study diligently. Isaiah’s words provide profound insights into the plan of salvation, the Atonement, and the latter-day gathering of Israel. Nephi uses Isaiah's writings to reinforce the message of redemption and hope through the Savior, Jesus Christ, emphasizing that righteousness and obedience lead to God’s blessings and protection.