Alma 6:1 he ordained priests and elders, by laying on his hands
A couple of items deserve mention. First, the phrase, "laying on [of] hands" is used only twice in the Book of Mormon, in Alma 6:1 and Moroni 2:1. It is interesting that this phrase is not used to describe the confirmation ordinance (see commentary for Mosiah 18:14). That it was used to ordain priests and elders is in accord with modern practices because it is according to the order of God in all dispensations.
Second, although it is clear that the Nephites had the Melchizedek priesthood, the offices in that priesthood were not structured exactly as they have been since the days of Christ. Rather the Book of Mormon speaks of four priesthood offices: high priest, elder, priest, and teacher (see commentary for Moroni 3:1). At this time, Alma is the only high priest (there is a similar pattern in the Levitical Priesthood under the Law of Moses). Alma's calling, then, was similar to what we know as the President of the Church, or the President of the High Priesthood of the Church (DC 107:65). Therefore, the term, "priests," as used in this verse has reference to an office in the Melchizedek Priesthood. Elder McConkie compared the Nephite office of "priest" in the Melchizedek Priesthood to the latter day calling of "high priest" in the Melchizedek Priesthood.
Bruce R. McConkie
"Book of Mormon prophets gave the title priest to officers known in this dispensation as high priests. That is, they were priests of the Melchizedek Priesthood, or as Alma expressed it, 'the Lord God ordained priests, after his holy order, which was after the order of his Son.' (Alma 13:1-20.) Since there was no Aaronic Priesthood among the Nephites in Alma's day (there being none of the lineage empowered in pre-meridian times to hold that priesthood), there was no need to distinguish between priests of the lesser and greater priesthoods." (Mormon Doctrine, p. 599)
Alma 6:3 those who were lifted up in the pride of their hearts...were rejected
Pride can be the underlying cause for excommunication when it leads to the breaking of sacred covenants. One of the less common ways this can happen is when the individual will not recognize the authority of the Lord's anointed servants. They become unable to submit to the counsel and recommendations of church leaders because their pride has elevated them, in their minds, above the counsel of the Church. Then and now, the sin of pride, when it leads to the spirit of apostasy, is grounds for excommunication.
Alma 6:5 the word of God was liberal unto all
"In teaching the gospel there is to be no distinction between the rich and the poor. The word of God is to be freely and generously given to all, regardless of social standing. 'For if there come unto your assembly a man with a gold ring, in goodly apparel, and there come in also a poor man in vile raiment; and ye have respect to him that weareth the gay clothing, and say unto him, Sit thou here in a good place; and say to the poor, Stand thou there, or sit here under my footstool: are ye not then partial in yourselves, and are become judges of evil thoughts?' (James 2:2-4.)" (McConkie and Millet, Doctrinal Commentary on the Book of Mormon, vol. 3, p. 47)
Alma 6:6 they should gather themselves together oft
Latter-day saints have no problem gathering themselves together oft. They are constantly meeting, sometimes for the sake of having a meeting. Sacrament meetings, however, are indispensable. Imagine what would happen to the ward if there were no opportunity to gather together, sing hymns, share the Spirit, and partake of the Sacrament. In the spring of 2020, the corona virus pandemic put a temporary stop to church services, but members were allowed to gather together and partake of the sacrament in their own homes. Whether in church or at home, the gathering allows an increased portion of the Lord's spirit according to the promise, For where two or three are gathered together in my name, there am I in the midst of them. (Matt. 18:20)
That Alma's people gathered in fasting and mighty prayer in behalf of the welfare of the souls of those who knew not God shows that they understood the meaning and purpose of their worship meetings.
Spencer W. Kimball
"We attend sacrament meetings to worship the Lord. If the meeting is conducted or if we attend with any other thought, we have missed the spirit of the occasion. Those who attend meeting only when the speaker is eloquent, the lecturer is noted, or the music is excellent, are far ahead of the high purpose and loftiness of this meeting in the house of prayer. It should be worship from the first announcement to the final prayer, consisting of the singing of sacred songs, prayers of gratitude, the partaking of the sacrament with appropriate thoughts, and the expounding of the gospel and bearing testimony of its divinity." (The Teachings of Spencer W. Kimball, p. 514)
"We do not want to neglect our prayers; we do not want to neglect attendance at our sacrament meetings. We do not want a spirit of darkness to come over us. I want to bear testimony to you Latter-day Saints, as a result of my own experience and training, and that of my children, that I know of no better way that we can keep the spirit of God burning in our souls and in their souls than by attending sacrament meetings." (Conference Report, Oct. 1945, p. 38)
Alma 6:8 the spirit of prophecy which was in him, according to the testimony of Jesus Christ
There is an inseparable relationship between the spirit of prophecy and the testimony of Jesus Christ. This doctrine is most classically found in Rev 19:10, where John tells us, the testimony of Jesus is the spirit of prophecy. Joseph Smith loved to refer to this passage because people so often were critical of the claim that he was a prophet.
"Many of the sects cry out, 'Oh, I have the testimony of Jesus; I have the spirit of God: but away with Joe Smith; he says he is a prophet; but there are to be no prophets or revelators in the last days.' Stop, sir! The Revelator says that the testimony of Jesus is the spirit of prophecy; so by your own mouth you are condemned." (The Teachings of Joseph Smith, by Dahl and Cannon, p. 662)
"If any person should ask me if I were a prophet, I should not deny it, as that would give me the lie; for, according to John, the testimony of Jesus is the spirit of prophecy; therefore, if I profess to be a witness or teacher, and have not the spirit of prophecy, which is the testimony of Jesus, I must be a false witness; but if I be a true teacher and witness, I must possess the spirit of prophecy, and that constitutes a prophet; and any man who says he is a teacher or a preacher of righteousness, and denies the spirit of prophecy, is a liar, and the truth is not in him; and by this key false teachers and imposters may be detected." (History of The Church, 5:215-16)
Alma had taught by this same spirit of prophecy. By the power of the spirit of prophecy and revelation, Alma is able to teach doctrines which were later taught in the New Testament. That these doctrines were revealed to him before they were revealed to Paul or John the Revelator should not surprise for they came through the spirit of prophecy. It is interesting to note that in the end of Alma 5, he speaks of the spirit of prophecy (Alma 5:47), then immediately gives his personal testimony of Jesus Christ (v. 48).
From the above, we learn that every member of the church should have the spirit of prophecy because every member of the church should have the testimony of Jesus. As Joseph Smith said, "a true teacher and witness...must possess the spirit of prophecy." This is true for every teacher and witness in the Lord's kingdom.
Joseph Fielding Smith
"The Prophet Joseph Smith has said that every member of the Church should be a prophet, meaning, of course, that he should have that testimony of Jesus and keep himself in perfect accord with the Spirit of the Lord so that he could recognize truth and the Lord could reveal the truth to him, so that he might comprehend it. Every man in the Church has the right to receive revelation for his own guidance, but not for the guidance of the Church." (Conference Report, Oct. 1943, p. 97)