Nephi lists two causes of the fall of his brethren: pride, and the temptations of the devil (v. 19). Mormon 1–6 discusses these two issues, but they will not be discussed at this time.
After seeing many generations pass away following the overcoming of his seed (v. 20), the angel tells Nephi that “these shall dwindle in unbelief” (v. 22). To dwindle is to gradually decline. History has proven the angel’s declaration. Nephi then observed that “after they had dwindled in unbelief they became a dark, and loathsome, and a filthy people, full of idleness and all manner of abominations” (v. 23). Mormon later uses basically the same descriptions as Nephi, but adds “beyond the description of that which ever hath been among us … because of their unbelief and idolatry” (Mormon 5:15). One of the purposes of the Book of Mormon is to correct the Lamanites’ unbelief and abominations and help them become “a pure and delightsome people” (2 Nephi 30:4–6). The restoration of those people is well underway. More about their restoration will be discussed in Chapter Twenty of this work.