After including these writings of Isaiah in his record, Nephi gave his future readers some keys for understanding Isaiah (see “Why Study Isaiah” and “How to Understand Isaiah,” preceding the commentary at 1 Nephi 20). One way to understand Isaiah, according to Nephi, is to know something “concerning the manner of prophesying among the Jews.” Looking back, we can see that that manner of prophesying was at least threefold: (1) dualistic, where a prophecy is fulfilled two or more times across dispensations; (2) messianic, with prophecies fulfilled in the first or second comings of Christ; and (3) parabolic, where a prophecy is given in the form of a story or parable.
To emphasize the significance of his insight about the manner of Jewish prophesying, Nephi stated that he avoided teaching his people and his children very much concerning the manner of the Jews because “their works were works of darkness, and their doings were doings of abominations.”
Even though Isaiah’s words were not so intelligible to Isaiah’s people and are still not clear to most people in our day, nevertheless, Nephi declared, “The words of Isaiah … are plain unto all those that are filled with the spirit of prophecy.” John wrote that the spirit of prophecy is “the testimony of Jesus” (Revelation 19:10). The Jews certainly did not have the testimony of Jesus, so they could not really understand Isaiah’s teachings. The same is true of us. Isaiah’s words will be plain and intelligible to those who have a real testimony of the Lord Jesus Christ—which means they have the spirit of prophecy—and who make the effort to understand the prophet’s words through diligent study accompanied by the Spirit of the Lord.