What does Acts 8:19 mean?

Simon, a magician in Samaria, has heard Philip's teaching about how Jesus of Nazareth is the Jewish Messiah, come to forgive the sins of the world. The message sounds good to him, and he agrees to be baptized (Acts 8:9–13). But when Peter and John lay their hands on his neighbors and the Holy Spirit comes down, his mind quickly sees the business opportunity.

Where Ananias and Sapphira wanted the notoriety of making a significant contribution to God (Acts 5:1–11), Simon apparently wants to use God for his own gain. This passage is the origin of the word "simony," which is the practice of buying or selling what only God can give, such as spiritual gifts or forgiveness, or should give, such as church offices.

Simon doesn't see the bigger picture. Although he is baptized, he doesn't understand that he needs to repent from his sins and be reconciled to God. He doesn't understand that Peter and John are laying their hands on the new converts to validate their entry into the church—the body of Christ—that will follow Jesus' teachings and suffer for it. He doesn't understand that the Holy Spirit promises eternal rewards in God's kingdom, not financial gain in the world.

He is about to learn how much his greed could cost him.