This verse is conceptually similar to Jacob’s definitions of Nephite and Lamanite:
Now the people which were not Lamanites were Nephites; nevertheless, they were called Nephites, Jacobites, Josephites, Zoramites, Lamanites, Lemuelites, and Ishmaelites.
But I, Jacob, shall not hereafter distinguish them by these names, but I shall call them Lamanites that seek to destroy the people of Nephi, and those who are friendly to Nephi I shall call Nephites, or the people of Nephi, according to the reigns of the kings. (Jacob 1:13–14)
In both cases, the label becomes detached from lineal descendants. Even as early as Jacob, “Nephites” are those friendly to “Nephi… or the people of Nephi.”
Mormon explains that the same labeling system endured throughout the Book of Mormon. “Nephites” believed in the records and the traditions of the Nephites. While Mormon adds a religious definition (“who believed in the commandments of God and kept them”), the modern distinction between religion and politics was not observed in the ancient world. (See commentary accompanying 2 Nephi 32:1.)
We should note also the dichotomous relationship between “Nephite” and “Lamanite.” For Jacob, those who opposed the Nephites were Lamanites. For Mormon, those who weren’t Lamanites were Nephites. Both prophets give only two categories, Nephite and Lamanite. Neither man, however, links those labels to lineage, as we might logically expect. These designations are broader than a kin group. They define a politico-religious body.