The teachings of Jacob clearly indicate that the early Nephites considered baptism an essential ordinance of the gospel. (2 Nephi 9:23-24.) Nephi also taught the necessity of baptism (2 Nephi 31:5-13), and then, referring to the baptism of the Savior, he counseled his followers to "do the things which I have told you I have seen that your Lord and your Redeemer should do; for, for this cause have they been shown unto me, that ye might know the gate by which ye should enter. For the gate by which ye should enter is repentance and baptism by water" (2 Nephi 31:17).
Concerning baptisms by the early Nephites, Joseph Fielding Smith has written:
The Book of Mormon teaches us that baptism for the remission of sins was a fundamental principle of the gospel among the Nephites from the time of Lehi all through their history. . . .All through the Book of Mormon there are references to baptism as an ordinance for the remission of sins. What their word for baptism was is not revealed, but in the translation the Prophet Joseph Smith used the familiar expression of our time. (Answers to Gospel Questions, 2:66.)
The Lord indicates in the Pearl of Great Price that baptism has been practiced as an ordinance of the gospel since the fall of Adam (Moses 5:58; 6:52), with Adam himself being baptized (Moses 6:64-65). The purpose and necessity of baptism is clearly and beautifully explained by the Lord in this scripture. (Moses 6:52-63.)
The following statement provides additional information on the baptisms performed before the birth of Christ:
In the former ages of the world, before the Savior came in the flesh, "the saints" were baptized in the name of Jesus Christ to come, because there never was any other name whereby men could be saved; and after he came in the flesh and was crucified, then the saints were baptized in the name of Jesus Christ, crucified, risen from the dead and ascended into heaven, that they might be buried in baptism like him, and be raised in glory like him, that as there was but one Lord, one faith, one baptism, and one God and father of us all, even so there was but one door to the mansions of bliss. Amen. (Times and Seasons, 3:905.)