... continued from yesterday.
The people listening to Peter are cut to the heart. Have you ever made a major mistake before, one that really hurt someone? Imagine making a mistake that got someone killed!
Many times, those in this situation refuse to admit that they have messed up, especially if clear wrongdoing or wrong motives are involved. No doubt many of those most responsible for Jesus' death fell into this category. But the crowd in Acts 2 do not have hard hearts. Peter does not specifically say here that they were the ones who had cried for Jesus' crucifixion, but they clearly recognized their past sins and need for God's forgiveness.
Peter gives the bottom line for salvation in Acts 2:38. It is similar to other verses like Romans 10:9 or John 1:12 that all point to the same basic attitude toward God. Peter says, "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."
To "repent" is to recognize that you have wronged God and others in the past and that you need God's grace and forgiveness. Luke-Acts does not focus so much on Jesus' death, but for the apostle Paul, Jesus' death made it possible for believers to get out from under the curse of sin (e.g., Gal. 3:13). But Acts focuses much more on Jesus' resurrection and the fact that it opened the door for the Spirit to cleanse our hearts.
Although Peter's sermon does not mention faith here, it is clear from elsewhere in Acts that "believing" or "having faith" in the message was a clear element in the process of getting right with God (4:4). Although the word "believe" and "faith" look quite different in English, they are actually the same root in Greek (pisteuo and pistis). Both words can focus on "head belief," and both words can lean more toward "trusting in" someone or something.
In this context, to believe the message is more than just checking "true" on a true/false test. Believing in the message implied in itself repentance from previous behavior and a turn to embrace a new direction and a new way of living. Faith implied commitment to everything the message implied as far as how to live and, more importantly, who to serve.
So repentance and faith were key elements of the response of the crowd. They also became baptized in water to symbolize the washing away of their past sins. It arguably was not the baptism itself that saved them from the judgment to come, but it was an important action. Symbolic actions are powerful, usually far more powerful than mere words or ideas.
We can get right with God without baptism--it happens to the Gentiles in Acts 10. They receive the Holy Spirit before they get to the baptism part. But why would we want to skip the power of such a sacred moment, a "sacrament" where God uses ordinary water to meet us in an extraordinary way?
Up to this point, the process of getting right with God has not differed from the process John the Baptist had brought to Israel at the beginning of Jesus' ministry. The baptism of the earliest Christians in Acts differed in one incredibly significant way. It involved receiving the Holy Spirit. The Holy Spirit sealed the deal.
The factor in the New Testament that shows par excellence that you are in the people of God in this age is the Holy Spirit. The Holy Spirit is the single determining factor of whether someone is in the people of God in the New Testament (e.g., Rom. 8:9). The Spirit can come whether a person is baptized or not. The Spirit can come on a child long before it has the presence of mind to repent or have faith (e.g., Luke 1:15). But if a person has not received or been filled with the Spirit, the person is not "in" the people of God in this final age.
The Spirit is God's "seal of ownership" on us (e.g., 2 Cor. 1:22), the stamp or brand that says we belong to God. The Spirit is a down payment of the kingdom, that guarantees us a place in it (2 Cor. 5:5; Eph. 1:14). Earlier in the chapter, we recognized that not everyone will have a deeply dramatic experience of the Holy Spirit. Most do not speak in tongues. Many experience a boldness to witness to Christ's power on their lives.
Most will have a sense of peace, but even here some need the body of Christ to speak God's love directly to them in ways they have difficulty feeling. Most will have a clear sense that God has washed away their past and cleaned up their lives. Most will have a new sense of the possibilities of the future, a future filled with goodness, love, and a live devoted to God.