What does Acts 2:38 mean?
It's likely that many in Peter's audience know of John the Baptist and even heard him preach. Those who accepted his words would have repented from their sins and been baptized to show that they affirm his message. And they would know that he did not claim to have any significance in and of himself, but that he was proclaiming that the Messiah was coming. In addition, John prophesied the Holy Spirit would come with fire, as He did just that morning (Acts 2:1–4), and the Messiah would give the Holy Spirit to His followers and destroy those who rejected Him (Matthew 3:1–12).So, Peter's words are familiar to any Jew who spends time in Jerusalem. The call to repent, be baptized, and receive the Holy Spirit is the same as that given by John, but the addition of Jesus' name is new. It marks the fulfillment of John's prophecy (Luke 3:16).
It seems that anywhere baptism is mentioned in the New Testament, confusion follows. It must be clear that baptism is no more required for becoming saved than putting on a jersey is required to officially join a sports team. We are saved by grace through faith (Ephesians 2:8–9), just as a professional football player is made a teammate by signing a contract. Baptism, like the uniform, is an outward, public sign, not a requirement in and of itself.
"Repent" is from the Greek root word metanoeo. It means to completely change one's paradigm, to admit error and accept the truth. In Christianity, it means to accept the viewpoint of God about the world, Jesus, and oneself, and act accordingly. "Forgiveness" is from the Greek root word aphesis. It is a pardon, granted by the victim of a crime or offense, whereby the victim agrees to relinquish his or her right to recompense from the perpetrator. In this case, God forgives our crimes against Him and places the burden on Jesus.
So it is that Peter calls the Jews to admit they are wrong, accept God's correct view of things, and trust that Jesus has paid for their sins. The crowd responds, and "there were added that day about three thousand souls" (Acts 2:41).