It is interesting to compare the words of the baptismal ordinance in Alma’s day to the latter-days. They are similar, but by no means identical. If Alma had used the modern day wording, he would have said, Helam, having been commissioned of Jesus Christ, I baptize you in the name of the Father, and of the Son, and of the Holy Ghost, Amen (DC 20:73). Although we like to think of things being done exactly the same way in every dispensation, the truth is that there was some variation in how ordinances have been performed in the past. Alma uses language in his baptism of Helam that was appropriate, approved in the sight of God, but different from our day. “Alma included a prayer for, we surmise, the benefit of Helam and also to impress on him and the others who waited for this glorious ministration, the importance of the covenant they made at that time.” (Reynolds and Sjodahl, Commentary on the Book of Mormon, vol. 2, p. 195) He emphasized the fact that baptism is a covenant to serve him until you are dead as to the mortal body. In fact, the ordinance of baptism had a slightly different connotation in Old Testament times. Although it still pointed to the redeeming sacrifice of Christ, the focus was on repentance and covenant making with God. This is why those who were baptized by John the Baptist had to be rebaptized:
’And he (Paul) said unto them, Unto what then were ye baptized? And they said, Unto John’s baptism.
Then said Paul, John verily baptized with the baptism of repentance, saying unto the people, that they should believe on him which should come after him, that is, on Christ Jesus.
When they heard this, they were baptized in the name of the Lord Jesus.’ (Acts 19:3-5)
Hugh Nibley
“[speaking of Alma’s pattern of baptism] …They’re following strictly the order before the time of Christ, and this is the order we find in the Dead Sea Scrolls, ‘as a testimony that ye have entered into a covenant to serve him until you are dead as to the mortal body’…[They were] looking forward to the pre-existent, eternal, unchanging gospel that’s to be given later.” (Teachings of the Book of Mormon, Lecture 36, p. 114)