Narrative: Having established a connection between the destruction of his people and the convincing of the gentiles that Jesus is the Christ, Nephi now returns to a more “chronological” discussion of how this is going to happen. Therefore, he leaves off the hints of the voice from the dust for the moment, and describes the future history after the destruction of his people.
Verse 18 once again plays on language from Isaiah:
5 Moreover the multitude of thy strangers shall be like small dust, and the multitude of the terrible ones shall be as chaff that passeth away: yea, it shall be at an instant suddenly.
Once again, Nephi ties Isaiah’s words into the new context of the destruction of his people. He has already noted that after the Spirit withdraws the end comes quickly (verse 11). He emphasizes the speed of that destruction with the reference to Isaiah.
Nephi also certainly understands that the Lamanites will survive the destruction of the Nephites. Nephi may be acknowledging that the Lamanites have had some semblance of the gospel when he notes that these events will come after they “have dwindled in unbelief.” This “dwindling” may be understood in one of two ways. The first is that “dwindling” is related to “unbelief.” The two are linked concepts, and it is the “belief” that “dwindles” into “unbelief.”
However, another interesting possibility is that Nephi understands that the destruction of his people may not be complete eradication, and there may yet be some remnant of his people in the New World when the gentiles come and “smite” them. Nephi does not specifically alter his focus from “his people” to “Lamanites,” which would be the normal understanding of those who remain. However, were we to use Lamanite in the generic, they certainly had not “dwindled” in population. While the Lamanites might be the ones who have “dwindled in unbelief,” there is nothing specific in Nephi’s text that would shift the focus from the Nephites to the Lamanites.