Paradoxically, on the other hand, as noted, because additional scriptures come forth only when the Gentiles “believe” the Book of Mormon—including its interpretation of the words of Isaiah (3 Nephi 26:7–11)—some must believe and understand them in order for that to occur. If not, if belief doesn’t involve acting upon it, how can it be called belief? Or, because Isaiah’s words are central to the Book of Mormon, how can misreading them be called belief? That again points to the dichotomy of some Gentiles repenting while others harden their hearts that underlines God’s dealings with the Gentiles (1 Nephi 14:1–7; 2 Nephi 6:12–13; 28:32; 3 Nephi 16:10–15; 20:15– 20; 21:6). When we inquire what is critical for the Gentiles to repent of “at that day”—causing them to fall prey to the entire catalog of crimes Jesus enumerates (3 Nephi 16:10)—the answer is surely their observing a lesser gospel than its fulness, one that lacks the wherewithal to ward against those evils (cf. Isaiah 50:10–11; 2 Nephi 28:26; Alma 12:11).
As time moves forward, moreover, if the Gentiles to whom the gospel was restored don’t make progress in understanding it, aren’t they in reality regressing? And if over time they mistake the gospel’s “lesser portion” for the “greater portion,” would they realize their error? Would they remember their saving role not only to themselves but to the house of Israel that is inherent in living the fulness of the gospel (Doctrine & Covenants 103:10)? Aren’t the Gentiles who repent the ones who “have care for the house of Israel” and “realize and know from whence their blessings come” (Mormon 5:10)—who act as “nursing fathers unto them” and their queens as “nursing mothers” (2 Nephi 10:9; cf. Isaiah 49:23; 60:9–11)? In short, aren’t the Gentiles who repent those who serve as saviors to the house of Israel (1 Nephi 22:6, 8; 2 Nephi 6:6–7; 10:8–9, 18; 3 Nephi 16:4–6) while those Gentiles who harden their hearts end up “fighting against Zion” and being “cut off” (1 Nephi 22:19; 2 Nephi 6:12–13; 3 Nephi 21:11, 20)?
(Excerpt from Endtime Prophecy, pp. 427-428)