Acts and the Holy Spirit
The Holy Spirit is a powerful force throughout Acts. In 2.1, we read that the disciples are together in Jerusalem at Pentecost. Pentecost is a Jewish festival that derives its name from the fact that it occurs fifty days after Passover. At this point in the narrative, the disciples have seen the risen Christ, and they have seen him ascend into heaven. They have also chosen a twelfth apostle, Matthias, who was a witness to the resurrection. However, they have not yet started to proclaim the message about Jesus. Something dramatic then happens which initiates the proclamation.
And suddenly from heaven there came a sound like the rush of a violent wind, and it filled the entire house where they were sitting. Divided tongues, as of fire, appeared among them, and a tongue rested on each of them. All of them were filled with the Holy Spirit, and began to speak in other languages, as the Spirit gave them ability (2.2-4).
This is the beginning of the outward expansion of the church. The Holy Spirit has initiated the mission. Jesus predicted this in 1.8 when he said,
"[Y]ou will receive power when the Holy Spirit has come upon you; and you will be my witnesses in Jerusalem, in all Judea and Samaria, and to the ends of the earth."
The Holy Spirit also plays an important role in conversion. Believers must receive the "gift of the Holy Spirit." For example, in 2.38-39, we read of Peter's instructions to a groups of Jews who wish to be converted:
Peter said to them, "repent, and be baptized every one of you, in the name of Jesus Christ so that your sins may be forgiven; and you will received the gift of the Holy Spirit."
Later in Acts we read of Paul's encountering a group of people in Ephesus. These people have been baptized with John's baptism, but they have not received the Holy Spirit. In 19.2-6, we read,
[Paul] said to them "Did you receive the Holy Spirit when you became believers?" They replied, "No, we have not even heard that there is a Holy Spirit." Then he said, "Into what then were you baptized?" They answered, "Into John's baptism." Paul said, "John baptized with the baptism of repentance, telling the people to believe in the one who was to come after him, that is, in Jesus. On hearing this, they were baptized in the name of the Lord Jesus. When Paul had laid his hands on them, the Holy Spirit came upon them, and they spoke in tongues and prophesied….
The Holy Spirit is important in a number of other ways, as well, such as in Christian prophecy and in the apostles' ability to perform miracles.
