The priests decided that they would try to trap Abinadi with questions. They read him a scripture and asked how he interpreted the passage. That passage is from Isaiah 52. Knowing that fact is very important because Abinadi answered by reciting the messianic Isaiah chapter 53 (see Mosiah 14). Thus, his real answer was, "If you want to understand Isaiah 52, you have to keep reading on into Isaiah 53." I often tell my law students that the first rule of statutory construction is read on, keep reading, and so it is with the first rule of scripture interpretation: read on. Do not take a scripture out of context. Do not stop reading too quickly. If you don’t understand a scripture, keep reading scripture.
But one must wonder, why did the priests think they could prove Abinadi to be a false prophet by quoting this passage from Isaiah 52? It is, at first glance, the strangest kind of approach by an accusing prosecutor we can imagine. However, they must have seen something in Isaiah 52 that other readers don’t. Indeed, they may have believed that Isaiah 52 was a prophecy about the city of Nephi and their greatness.
Look at it from their point of view. The passage begins, "How beautiful upon the mountains." Ah, mountains! The city of Nephi is up in the mountains. "How beautiful upon the mountains are the feet of … who?" The feet of a person who brings good tidings. However, Abinadi had not brought good tidings, but rather condemnations and woes. "Thy watchmen shall lift up the voice." One of the major projects of King Noah was the construction of a tower. He has watchmen all over. "With the voice together shall they sing … for the Lord hath comforted his people, he hath redeemed Jerusalem." (Mosiah 12:21–24, quoting Isaiah 52:7–10). Zeniff’s and Noah’s people believed they had gone back to the city of Nephi and redeemed the land. I will bet they used this very scripture to reinforce their city’s creation story. This is their main scripture. It justifies building watchtowers; it justifies redeeming the land; it glorifies living in comfort! It probably was one that they cited many times saying, "The Lord is with us," for as the true prophet said, "Thy God reigneth!" (Isaiah 52:7). That is why they asked Abinadi how to explain this scripture. This, they thought, was talking about them and all was well.
Book of Mormon Central, "Why Would Noah’s Priests Quiz Abinadi on Isaiah? (Mosiah 12:20–21)," KnoWhy 89 (April 29, 2016).
Dana M. Pike, "’How Beautiful upon the Mountains’: The Imagery of Isaiah 52:7–10 and Its Occurrences in the Book of Mormon," in Isaiah in the Book of Mormon, ed. Donald W. Parry and John W. Welch (Provo, UT: FARMS, 1998), 261–265.