"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. The promise is for you and your children and for all who are far off- for all whom the Lord our God will call.'" NIV translation
Peter is telling the crowd what they should do to be saved from the effects of their sins. It begins with repentance which is a changing of the mind to bring it into agreement with the will of God. The second is baptism which is an act of identifying oneself with the savior, Jesus Christ. Then, God promises us, through Peter, that we will receive the Holy Spirit. This is the same thing that happened to Jesus when he was baptized. This gift will help us to conform our actions as well as our minds to the will of God. Finally, Peter tells the crowd that this promise is for everyone. This probably amazed the crowd because, in the mind of the Jews, salvation was only for the chosen people of God (Israelites).
"With many other words he warned them; and he pleaded with them, 'Save yourselves from this corrupt generation.' Those who accepted his message were baptized, and about three thousand were added to their number that day." NIV translation
Up to this time, Peter has been trying to use logic and to reason with this crowd using the scriptures. Now, he turns to warning them about the effects of ignoring the word and pleads with them to accept the sacrifice of Jesus Christ. I wonder if we are as fervent in our attempts to tell people about Jesus. In the end, we see that God was at work in the crowd and three thousand came to Christ.
That is a good example for us in that, if we are faithful in telling the world the gospel, God will do the work and call people to him.
"They devoted themselves to the apostles' teaching and to the fellowship, to the breaking of bread and to prayer." NIV translation
This verse is telling us what the new believers did to grow in their faith. At this time, people did not have Bibles because they were too expensive. Therefore, the new believers gathered with the apostles to learn about Jesus. Today, most of us have a Bible and we can learn more anytime we want but we should still get together with other Christians to study as well as for fellowship. It is tough to be a follower of Christ and it is good to get together with other Christians for encouragement. This verse also tells us that they got together for the breaking of bread. They did this as a remembrance of Jesus, just as he had instructed the disciples at the last supper. Finally, we are told that they gathered for prayer.
"Everyone was filled with awe, and many wonders and miraculous signs were done by the apostles." NIV translation
Does the phrase "filled with awe" describe you and your relationship with Jesus Christ? For me, just the fact that the Son of God left heaven to come and suffer in my place fills me with awe. Then, you add on the fact that God knew that it was going to be necessary even before the fall of man in the garden. That is filled with awe to me. The last part of the verse goes on to say that wonders happened through the apostles. Sometimes, I wonder if we realize that God did not stop doing amazing things after the apostles were gone. Is God doing wonders and miraculous signs with your life? Are people coming to Christ by watching your example? God is still into using his people to change the world. If you are his, then he wants to do wonders and miraculous signs through your life.