In regards to setting the church in order, President Joseph F. Smith, in speaking of offices in the Melchizedek Priesthood remarked:
… if it were necessary, though I do not expect the necessity will ever arise, and there was no man left on earth holding the Melchizedek Priesthood, except an elder—that elder, by the inspiration of the Spirit of God and by the direction of the Almighty, could proceed, and should proceed, to organize the Church of Jesus Christ in all its perfection, because he holds the Melchizedek Priesthood.
Why Alma ordained “one priest to every fifty of their number” (Mosiah 18:18) is not stated. Perhaps a similar organization was followed by Zeniff who may have learned it from the plates of brass. Moses had “the Holy Priesthood, which he received under the hand of his father-in-law, Jethro” (D&C 84:6). Moses followed his counsel in making “heads over the people, rulers of thousands, rulers of hundreds, rulers of fifties, and rulers of tens” (Exodus 18:21–25). Having only two hundred and four people, Alma may have begun at the fifties division set up by Moses. The principle of teaching nothing but what the prophets had taught he had learned from Abinadi (see Mosiah 14:33; 15:11–16), or from the Spirit of the Lord that was upon him. To preach nothing but repentance and faith on the Lord (Mosiah 18:20) is similar to the modern revelation that the thing “of the most worth unto you will be to declare repentance unto this people, that you may bring souls unto [Christ]” (D&C 15:6). Faith is implied in the statement. Having “one faith and one baptism” (Mosiah 18:21) may also have been taken from the plates of brass. Paul taught it to the Ephesians (4:5) and may have been quoting from the Old Testament as he so often did. Alma’s organization was successful, they become the children of God (v. 22).