This doctrine is so important that it appears in 5 different places in the scriptures: Micah 5:8-9, 3 Nephi 16:15; 20:16; 21:12; Mormon 5:24. Here, the Lord references the prophecies of Micah 5:8-9. He explains that the remnant spoken of will include the latter-day descendants of the Nephites and Lamanites. This is the time spoken of when Jacob shall flourish in the wilderness, and the Lamanites shall blossom as the rose (DC 49:24). But the remnant spoken of will also include all those Gentiles who have repented and been adopted into the House of Israel (see commentary for 3 Nephi 16:15). Therefore, the best way to think about this remnant is as the kingdom of God on earth or the Church of Jesus Christ of Latter-day Saints, for they are the covenant people of the Lord (see v. 19). It is in this context, as members of the church and kingdom of God, that the Lamanites will blossom.
According to the prophecy, this remnant is to be feared, for they are they, who…if [they] goeth through both treadeth down and teareth in pieces, and none can deliver. Well this prophecy sounds quite ominous! Do the Gentiles of the Latter-days need to fear the Church of Jesus Christ of Latter-day Saints? According to the word of the Lord, they need to fear the power of God which will be among this people in the last days, for they shall have power after many days to accomplish all things pertaining to Zion (DC 105:37). One might think this prophecy sounds too violent. Certainly, it is hard to imagine the Church as a military threat to the Gentiles. Yet, over the course of the next several verses, we will see that the power of the Lord will be among the saints to such a degree that it will strike fear into the hearts of the Gentiles. They may, even as prophesied, go through, treading down and tearing in pieces, but the final destruction will be at the hand of the Lord himself, I will tread down the people in mine anger, and make them drunk in my fury, and I will bring down their strength to the earth (Isa 63:6).
Bruce R. McConkie
"Except for a few who are the humble followers of Christ, the Gentiles will not repent. They will revel in their abominations and sin against the restored gospel, and they will be burned by the brightness of our Lord's coming while the righteous -- here called the remnant of Jacob -- shall abide the day. And then, in the prophetic imagery, it will be as though the remnant of Israel overthrew their enemies as a young lion among the flocks of sheep." (The Millenial Messiah, p. 248)