The Amalekites, Amulonites and other Nephite Dissenters
We know who the Amulonites are. Amulon was one of the wicked priests of Noah. He along with the other priests left their wives and children and hid in the wilderness while the Lamanites attacked the Nephites. Later, these priests would capture 24 Lamanite women and make them their wives. These are the Amulonites.
We do not know the history of the Amalekites, but we do know that they are Nephite dissenters. Since the Amulonites would have known nothing of Nehor, perhaps the Amalekites were an offshoot of the Nehors and subsequently introduced this religion to the Amulonites and Lamanites. We read in Alma 21:4 that the Amalekites and Amulonites "were after the order of the Nehors."
This information about these two Nephite-dissenting groups is critical in the Book of Mormon history. We will later read that it is the Amalekites and Amulonites who are responsible for stirring up the Lamanites against the people of Ammon or the Anti-Nephi-Lehies. After attacking the Anti-Nephi-Lehies, many of these Lamanites are "pricked" because they killed many Anti-Nephi-Lehies in cold blood (the Anti-Nephi-Lehies didn't defend themselves). This caused the Lamanites to become angry at the Amulonites (Alma 25:6-12) and consequently hunted down and killed the surviving Amulonites.
For some reason the Amalekites do not receive any Lamanite backlash. The Amalekites survive and thrive in the Lamanite nation. They later play a key role in that they lead the Lamanites (or are placed as leaders by the Zoramite Zerahemnah) against the Nephites after the Zoramites dissent to the Lamanites. The Nephites defeat the Lamanite-Amalekite-Zoramite army (Alma 43 and 44).
After the Anti-Nephi-Lehi wars end, we read of yet another dissenter - Amalickiah. He too would depend on the hardness of the Nephite dissenters to lead his campaign against the Nephites. Just as the Zoramites appointed Amalekites captains (Alma 43:6), Amalickiah appoints Zoramites to be captains of his armies. (Alma 48:5)
It is interesting to note that all of these wars began because of the religious division between the alliance of the converted Lamanites and Nephites and the alliance of the non-converted Lamanites and Nephite dissenters. (see Alma 24:1, Alma 27:1-2, Alma 28:1-2, Alma 35:10-11) I term these wars the Anti-Nephi-Lehi wars. The difference between these wars and the Big War is that Amalickiah does not direct is wrath at the Anti-Nephi-Lehies … rather he seems to posses an overall hatred for the Nephites.
The Dissenters' Belief
The reason Alma 21 is so significant is that it provides us a brief insight into the beliefs of the Nephites dissenters. There is an exchange between an Amalekite and Aaron in Alma 21:5-10 that demonstrates their attitudes and beliefs. The Amalekites seem to take great offence when Aaron tries to teach them the truthfulness of the gospel. The Amalekites believe that by simply having a religion and worshipping a God, they are sufficiently keeping the commandments. The fact that they may not be worshipping the true and living God and that they do not know or believe in Christ does not bother them in the least.
Today, Satan uses this same line of reasoning to keep many away from the truth. It is the notion that "All Roads Lead to Rome" and that as long as you are religious, then you will be saved. This thinking is all relativistic. Compared to blatant sinners or those who have no morals, a person who has a religion and practices it looks like an angel. But just because a person has a religion does not mean they have the truth. If you are going to worship, then worship the true God. The Lord wants us to be certain and true in our testimony. Revelation 3:15-16 teaches us this concept. "I know thy works, that thou are neither cold nor hot: I would thou were cold or hot. So then because thou are lukewarm, and neither cold nor hot, I will spue thee out of my mouth."