When the day of Pentecost came, they were all together in one place. Suddenly a sound like the blowing of a violent wind came from heaven and filled the whole house where they were sitting. They saw what seemed to be tongues of fire that separated and came to rest on each of them. All of them were filled with the Holy Spirit and began to speak in other tongues as the Spirit enabled them. Acts 2:1-4

When the apostles in Jerusalem heard that Samaria had accepted the word of God, they sent Peter and John to them. When they arrived, they prayed for them that they might receive the Holy Spirit, because the Holy Spirit had not yet come upon any of them; they had simply been baptized into the name of the Lord Jesus. Then Peter and John placed their hands on them, and they received the Holy Spirit. Acts 8:14-17

During the time of John the Baptist and Jesus, people responded to the message of repentance by stating they were a sinner, acknowledging God (or later Jesus’ death on the cross) and getting baptized.

Then, at Pentecost (Acts 2), a new step in a believer’s relationship to God was added--the Holy Spirit literally entered their lives. In the Old Testament, the Spirit only entered certain people giving them extraordinary talents or strength. Now, as promised by Jesus (John 16), the Holy Spirit came into all believers in a powerful way. Jesus, after the resurrection, breathed the spirit into the apostles (John 20), a precursor to others receiving that same spirit.

In Acts 2:1-4, the Holy Spirit, at Pentecost, gave the ability to speak in other tongues, or languages/dialects. This occurred only briefly, to showcase God’s call for us to reach the whole world. This had a dispersing effect, calling those who received the Holy Spirit to go into the whole world, to all tribes and languages. Their “speaking in tongues” showed them that God could overcome any obstacle on their quest to evangelize the world, including the excuse of not speaking different languages. However, there is no indication that they permanently received a new language.

In Acts 8, we see some who were baptized earlier, but had not received the Holy Spirit. Those believers had only heard about Jesus, but had no idea about the Holy Spirit. The apostles wanted to make sure they got the full upgraded spiritual package. Christianity 2.0.