Baptism is not essential to one's reception of salvation. It is a symbol of one's identification with the life, death, and resurrection of Jesus Christ. The proper mode is immersion in the triune name of the Father, the Son, and the Holy Spirit. Acts 2:38 must be read in context and in light of Jesus' clear command in Matthew 28:19.
Always interpreting Acts 2:38 in light of Oneness doctrine, and not truly in the light of "the whole counsel of God" despite misinterpreting lots of "supporting scriptures" to maintain your Oneness convictions doesn't benenfit you.
As ex-Oneness Pentecostal but now living in the truth of God's Word Mike Barden points out:
When we correctly understand the meaning of Acts 2:38, the whole Oneness "gospel" gets dismantled; it cannot exist without misinterpreting this verse.
Let's look at this verse, phrase by phrase, in light of all that has already been established about water and Spirit baptism (I'll use the King James Version, as would most Oneness Pentecostals):
"Then Peter said unto them,": The apostle Peter never heard Jesus teach that baptism was essential to forgiveness, and in his later preaching, Peter never taught it again. Unless Peter was mentally unstable, or grossly mistaken, he would not preach a different message in this sermon than what Jesus taught him, nor would he preach a different message here than he would anywhere else.
"Repent,": Repentance is simply "a change of mind." This is the true moment of Christian conversion, when a person stops living according to their own selfish desires, and starts living according to the promises and will of God. In the Greek text, this command is in the second person plural; it is addressed to the crowd as a whole. This is significant, as we will soon see.
"and be baptized every one of you": This is indeed a command to be baptized in water, but it is given in the third person singular, addressed to specific individuals who would soon come to saving faith. Again, the significance of the grammar will soon be apparent.
"in the name of Jesus Christ": Oneness adherents insist that this means that the words "in the name of Jesus Christ," or some equivalent, be spoken by the baptizing pastor at the time of the baptism. Biblically, however, to do something in someone's name means it is simply done in the authority and place of that person. This may or may not be accompanied by spoken words; Christians are commanded to do all things "in the name of Jesus Christ," but we are surely not expected to say "in the name of Jesus Christ" whenever we do anything. If a person is baptized as a submission to the authority of Jesus Christ, they are baptized "in the name of Jesus Christ," no matter what was spoken by the baptizing pastor.
"for the remission of sins,": Remember, remission is the same as forgiveness, which was already discussed in relation to Romans 4. The Greek word translated "for" is eis, which has two legitimate biblical meanings. It can mean "for the purpose of," or it can mean "because of." Depending on how you translate it, Peter is either preaching baptism "for the purpose of" forgiveness yet to be received, or baptism "because of" forgiveness already received. In light of the teaching in Romans 4:7-8, we know that God's forgiveness comes at the moment of justification, which happens when a person trusts in God's provision of salvation through the death and resurrection of Jesus (Romans 4:23-25). Knowing this fact, we must assume that Peter was commanding new believers to be baptized "because of" the forgiveness they would have received at the first moment of their faith.
"and ye shall receive": This last part of Acts 2:38 is now back to second person plural, addressed to the whole crowd of listeners. This fact is reflected in the King James translation, which uses the word "ye" (plural) in this phrase, and the word "you" (singular) in the command to "be baptized." The significance of this grammar is that "the gift of the Holy Ghost" is connected directly to repentance, not water baptism. The middle command to "be baptized" is a parenthetical command, addressed to those individuals who would already have repented and been forgiven.
"the gift of the Holy Ghost.": Notice also that Peter never teaches a prerequisite "seeking" in order to receive the Holy Spirit ("seeking," or "tarrying," is a common situation in most Oneness churches, and can include kneeling, praying, crying, continuous "repenting" of sins, raising of the hands, saying "hallelujah" repeatedly, etc.; this process may be only for a few minutes, or it may be repeated over a span of years). The Holy Spirit is a free gift, and He comes directly and instantaneously to the person who truly repents. For more about the exact nature of the Holy Spirit, go back to the previous section on "the Spirit."
When we see the real, simple message of Acts 2:38, we see that it does not at all support the "gospel according to Oneness Pentecostalism," but that it teaches a simple, powerful message of the grace and love of God to those who would come to Him.
Now that we've examined the heart of Oneness Pentecostalism's error, we can now more easily understand some of the other "bitter fruit" that grows out of this false "gospel."
Praise the Lord that Mark is now walking in the truth of God's Word free form Oneness Doctrine.
http://www.gospeloutreach.net/opgospel.html
One final thought regarding Water Baptism in the Triune formula. In Matthew 16 verses 18+29; we see where Jesus gave Peter the "keys" whatsoever those shalt bind on earth., shall be bound in heaven"
Notice The Man with The "keys" by God's own Authority, told everyone gathered in the upper room, at the very first church service, to be Baptized in The Name of Jesus Christ, did he not? (Acts 2 v 38). So there is only a couple of conclusions we can come to
1. He knew Jesus is THE NAME of The Father, Son, Holy Ghost.
2. He disobeyed what Jesus said to do LITERALLY., and therefore lied to everyone at the first Church service.
I vote for #1.....Other wise Peter does not deserve to have the "keys" Jesus awarded him....