The Meaning of Acts 2:38
Peter replied, "Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive the gift of the Holy Spirit" — Acts 2:38, NIV
Peter's statement is in response to a request by his audience of "what shall we do?" They wanted to know what they could do about the state of sin they found themselves in after being convicted through Peter's preaching about the crucified Messiah. Peter's response directs them (and us) to a course of action. Two imperatives are given and two results that follow adherence to the imperatives.
"Repent" is second person imperative, indicating a mandate for all to repent. To repent (metanoeo) means to not only feel sorry for your sins but to be willing to change your behavior in obedience to God's commands. F.F. Bruce (p. 75, Acts Commentary) explains that to repent means to have a, "complete change of heart, a spiritual right-about-turn." In this context repentance is mentioned as the first condition because the thing foremost in the minds of Peter's audience is the conviction of their sins. Peter is telling them that the first thing they can do about their sins is repent of them, turn away from them.
The second imperative concerns baptism. "Be baptized" is third person passive imperative, stressing individual responsibility to obey. This is referring to water baptism for the following reasons: 1) Peter is speaking of the baptism of the Great Commission which was to be administered by the apostles themselves; 2) the baptism was something Peter's hearers must do; "what shall we do?" (vs. 37)was the question and Peter's answer was "...be baptized".; 3) Peter's baptism would have recalled to his audience's memory the baptism of John (Mark 1:4) which was definitely a baptism in water.
Repentance and baptism are joined together by the word "and". If repentance is accepted as a condition for forgiveness, baptism must be accepted along with it. The two cannot be separated. The purpose of obedience to these two imperatives is "for" (eis) the remission of sins and to receive the gift of the Holy Spirit. The word "for" (eis) has as its most common meaning the direction or motion toward something, which includes the concepts of purpose and goal. The purpose and goal of repentance and baptism is to receive the forgiveness of sins and the gift of the Spirit. It must be remembered that Peter's answer was in response to a question of how to remove one's sin/guilt. His answer was, "do these two things (repent and be baptized) and you will receive these two things (forgiveness, Holy Spirit)."
The implications of this throughout Acts is that baptism always accompanied the salvation experience. There are no exceptions to this. Bruce (Commentary, p. 77) in a parenthetical note remarks, "the idea of an unbaptized Christian is simply not entertained in the NT." Although it can be debated when the reception of the Holy Spirit occurred in some of the Acts narrative, there can be no debate that everyone was baptized.
The implications for today would be the same. It is foreign to the New Testament to conceive of a person receiving the forgiveness of sins and the gift of the Spirit without first obeying the imperatives to repent and be baptized. Although most of the Christian world has no problem accepting the first imperative the second one is problematic. Usually this is because baptism is mistakenly considered a work and since we are not saved by works it is rejected as a condition of salvation. But baptism is not presented as a work in the New Testament, rather, it is an act of faith and obedience to God.