Mormon equated these saving ordinances with miracles which he said had not ceased since the coming of Christ in the flesh, neither had angels ceased to minister to men (vv. 27–29). There are two prerequisites for angels to minister to men: first, angels must be commanded by Jesus to come; and second, the recipient must be “of strong faith and a firm mind” (v. 30).
There are two basic purposes for angels calling upon men: (1) to call people to repentance, and (2) to fulfill and to do the work of the covenants of the father (v. 31). The calling of men to repentance is illustrated in various places in the Book of Mormon—an angel called Laman and Lemuel to repentance (see 1 Nephi 3:29), and one appeared to Alma and the sons of Mosiah and did the same thing (see Mosiah 27:11).
The appearance of angels to fulfill and to do the work of the covenants of the Father is the work of providing ordinances for the salvation of man. For ordinances to be efficacious in the lives of men, they must be done by the authority of the priesthood. The keys of the priesthood are the directing power of the priesthood. Therefore, when apostasy has occurred and the keys of the priesthood have been lost, it is necessary to restore these keys again.
God has used angels to restore these heavenly keys. In our own dispensation, John the Baptist restored the keys of the Aaronic Priesthood (see D&C 13); Peter, James, and John restored the keys of the Melchizedek Priesthood (see D&C 27:12–13). Moses brought back “the keys of the gathering of Israel,” Elias “the dispensation of the gospel [covenant] of Abraham,” Elijah the keys “to turn the hearts of the fathers to the children and the children to the fathers” or the patriarchal priesthood (see D&C 110:11–16; see also TPJS, 323), “and of divers angels, from Michael or Adam down to the present time, all declaring their dispensation, their rights, their keys, their honors, their majesty and glory, and the power of their priesthood” (D&C 128:21).
Thus the way is once more prepared for the children of men to attain salvation through the exercise of faith and the obtaining of the ordinances of the priesthood. The chosen vessels of the Lord (priesthood leaders) bear testimony of Christ, and provide the ordinances necessary for salvation through him (baptism, sacrament, conferring the Holy Ghost), and thus the covenants of the Lord are fulfilled (Moroni 7:31–32). By faith, miracles are performed, angels minister to men, and the residue of men (mortals living on earth) may, through their faith, accept the opportunity to participate in those saving ordinances (vv. 33–34).