According to Robert Millet, in reading Alma 13 in context--as part of a larger sermon--we begin to see that the idea of entering the rest of the Lord is a central theme. The word rest is mentioned in each of the final four verses of the preceding chapter. It is mentioned five times in chapter 13. It would appear that Alma is trying to point out that it is through the atoning blood of Christ and by the power of the holy priesthood that individuals and congregations are prepared and made ready to enter the rest of God.
In one sense, a person enters the rest of God when he or she gains a testimony of the gospel, and is brought out of worldly confusion into the peace and security that comes only from God. In this sense, the rest of God is “the spiritual rest and peace which are born from a settled conviction of the truth in the minds of [individuals].” (Smith, Gospel 126; see also 58). It is to know the peace of the Spirit, to enjoy the blessing of the Comforter. It is what Jesus promised to disciples when he said: “Come unto me, all ye that labour and are heavy laden, and I will give you rest” (Matthew 11:28).
Second, spirits enter the rest of God when they enter paradise, the home of the righteous in the postmortal spirit world at the time of death (Alma 40:11-12; 60:13).
A third dimension of the rest of the Lord is that which follows the resurrection and judgment, as we enter the celestial kingdom and receive exaltation (see Moroni 7:3)… .
There is yet another sense in which the word rest is used in scripture… . In D&C 84:19-25 the rest of the Lord is equated with being in the personal presence of the Lord while the recipients are still mortal… .
It appears that the concept of the “rest of the Lord” is used occasionally in terms of what other scriptures call the Church of the Firstborn (see Hebrews 12:23; D&C 76:54). The Church of the Firstborn is the church of the exalted, an organization of saved souls, a body of believers who have passed the tests of mortality and received the approval of God. They qualify for life in the celestial kingdom, and because they have been true to all their trusts, are worthy to be joint heirs with Christ, co-inheritors with him to all of the blessings of the firstborn (see Smith, Doctrines 2:42; Man 272; The Way 208; McConkie, Mormon 139-40; The Promised 47). The phrase “Church of the Firstborn” is not found in the Book of Mormon, but it may be that to enter the rest of the Lord is to enter the Church of the Firstborn. In speaking of the ancient worthies, Alma said: “They were called after this holy order, and were sanctified, and their garments were washed white through the blood of the Lamb. Now they, after being sanctified by the Holy Ghost, having their garments made white, being pure and spotless before God, could not look upon sin save it were with abhorrence; and there were many, exceedingly great many, who were made pure and entered into the rest of the Lord their God” (Alma 13:11-12).
The ultimate privileges of God’s holy authority are spoken of as follows. The power and authority of the higher, or Melchizedek Priesthood, is to hold the keys of all the spiritual blessings of the church--to have the privilege of receiving the mysteries of the kingdom of heaven, to have the heavens opened unto them, to commune with the general assembly and church of the Firstborn, and to enjoy the communion and presence of god the Father, and Jesus the mediator of the new covenant.“ (D&C 107:18-19) [Robert L. Millet, ”The Holy Order of God," in The Book of Mormon: Alma, The Testimony of The Word, pp. 72-75]
Note* In view of these ideas by Robert Millet, Alma2 was apparently preaching that man (any man) who repented, entered into, and faithfully obeyed the covenants of the Lord could become like Him; that is, that they could become a God. The reader should keep in mind that Alma2 was preaching these ideas to a possible dissident Mulekite (Jewish) audience in Ammonihah who believed that they descended from the chosen people of the Lord (see Alma 31:18,28 for a comparison with the Zoramites). Amaleki says that when Mosiah1 first found the people of Zarahemla (Mulekites--Mosiah 25:2) that “they denied the being of their creator” (Omni 1:17). Are we to surmise by his statement that many of the Mulekites (people of Zarahemla) denied the “existence” of their creator, or did Amaleki mean that many of the people of Zarahemla did not comprehend the “character” of their creator? In other words, did many of the Mulekites refuse to accept the idea that “the Creator” was Christ, the Savior, the Son of God, the sacrificial Lamb of God, anointed to atone for the sins of the world? If the Mulekites denied the “being” or character of their Creator, then they apparently carried on the same beliefs and attitudes that led the Jews to reject Moses’ challenge to be “sanctified” (through priesthood covenants) while in the wilderness (D&C 84:19-25), the same beliefs and attitudes that led the Jews at 600 B.C to desire the death of Lehi (1 Nephi 1:19-20), and the same beliefs and attitudes of the Jews in Christ’s day who would crucify one Jesus of Nazareth, because they apparently expected their savior to be only a servant of God (“the Messiah”) who would establish them (in their sins) before the world as the chosen people of God by birth, for they were “the children of Abraham” (see Matthew 3:9).
The Jews could not accept that the “being of their Creator” (Jehovah) could become mortal as Jesus Christ. Neither could they accept a mortal man becoming or being a God. In their view, Alma was preaching to them an unacceptable priesthood covenant way. Their blessings were all derived from Abraham. Alma, however, showed them from the scriptures not only how the order of the priesthood of Melchizedek was above their understanding of the priesthood held by Abraham, but in a similar manner how the order of the Son of God (Christ--the Creator) was the prototype of the priesthood order of Melchizedek. In the Old Testament we find that the “rest of the Lord” implies a process complete (or perfect)--“on the seventh day God ended his work which he had made; and he rested …” (Genesis 2:2). Alma apparently understood that to enter into “the rest of the Lord” is to “choose” righteousness (Alma 13:10), be made “pure and spotless before God” (Alma 13:12), and to keep the priesthood covenants perfectly (see Alma 27:27), as did the Son of God--Christ--the Creator. [Alan C. Miner, Personal Notes] [See Thomas Cherrington’s commentary on 1 Nephi 1:19-20]