Reading these verses, one may wonder whether Nephi did not already have priesthood authority and whether the ordinance of baptism was not already being practiced among the Nephites. The answer to both questions would be yes. Nephi already had authority, and baptism was already being practiced.
The doctrinal significance of these verses is not merely to reiterate the importance of baptism by the proper priesthood authority but rather to demonstrate the establishment of a new gospel dispensation among the Nephites and the accompanying ordinations and ordinances that a new dispensation necessitated. Of the events described in these verses, President Joseph Fielding Smith taught: “There is nothing strange in the fact that when the Lord came to the Nephites, Nephi was baptized and so was everybody else although they had been baptized before. The Church among the Nephites before the coming of Christ was not in its fulness and was under the law of Moses. The Savior restored the fulness and gave them all the ordinances and blessings of the gospel. Therefore, it actually became a new organization, and through baptism they came into it.
We have a similar condition in this dispensation. The Prophet Joseph Smith and Oliver Cowdery were baptized by command of the Angel John the Baptist. Several others were baptized before the organization of the Church. However, on the day the Church was organized, all who had been previously baptized were baptized again, not for the remission of sins, but for entrance into the Church. In each case the reason was the same.” (Answers to Gospel Questions 3:205-6; see also 4:96-97.)
“Ye Shall Never Taste of Death”
All men and women die. No person, not even a translated being immunity from death. Joseph Smith taught that “translated bodies cannot enter into rest until they have undergone a change equivalent to death” (Teachings, p. 191) The righteous, which would include translated beings, though they face death, do not taste death. Paul taught that “the sting of death is sin” (1 Corinthians 15:56). “
Thou shalt live together in love,” Christ counseled his Latter-day Saints, “insomuch that thou shalt weep for the loss of them that die, and more especially for those that have not hope of a glorious resurrection. And it shall come to pass that those that die in me shall not taste of death, for it shall be sweet unto them.” (D&C 42:45-46, italics added.) For translated beings death i postponed in order that they can continue their ministries.