IN those days, as the apostles were going to the place of prayer, we met a slave-girl who had a spirit of divination and brought her owners a great deal of money by fortune-telling. While she followed Paul and us, she would cry out, “These men are servants of the Most High God, who proclaim to us a way of salvation.” She kept doing this for many days. But Paul, very much annoyed, turned and said to the spirit, “I order you in the Name of Jesus Christ to come out of her.” And it came out that very hour.
But when her owners saw that their hope of making money was gone, they seized Paul and Silas and dragged them into the marketplace before the authorities. When they had brought them before the magistrates, they said, “These men are disturbing our city, they are Jews and are advocating customs that are not lawful for us as Romans to adopt or observe.” The crowd joined in attacking them, and the magistrates had them stripped of their clothing and ordered them to be beaten with rods. After they had given them a severe flogging, they threw them into prison and ordered the jailer to keep them securely. Following these instructions, the jailer put them in the innermost cell and fastened their feet in the stocks.
About midnight Paul and Silas were praying and singing hymns to God, and the prisoners were listening to them. Suddenly there was an earthquake, so violent that the foundations of the prison were shaken, and immediately all the doors were opened and everyone’s chains were unfastened. When the jailer woke up and saw the prison doors wide open, he drew his sword and was about to kill himself, since he supposed that the prisoners had escaped. But Paul shouted in a loud voice, “Do not harm yourself, for we are all here.” The jailer called for lights, and rushing in, he fell down trembling before Paul and Silas.
Then he brought them outside and said, “Sirs, what must I do to be saved?” They answered, “Believe in the Lord Jesus, and you will be saved, you and your household.” They spoke the word of God to him and to all who were in his house. At the same hour of the night he took them and washed their wounds, then he and his entire family were baptized without delay. He brought them up into the house and set food before them, and he and his entire household rejoiced that he had become a believer in God.
Christ is risen!
The girl who was a "fortune-teller" was possessed by a demon. In the Gospel accounts we sometimes see demons recognize and proclaim Jesus as the Son of God and God Himself. Unlike people, demons always recognize Jesus for Who He is. And in the passage above, we see a demon recognize Christ's disciples for who they are - His followers, proclaimers of the way of salvation, which is only through Jesus Christ.
Jesus never allowed demons to Him as God, and Paul also disallows the demon witness to the work of the apostles. He cast out the demon, by the power of Jesus Christ, and healed the poor girl. As the Orthodox Study Bible notes, every baptismal service in the Orthodox Church begins with an exorcism to expel satan from having any further influence over the new believer. This does not mean that every person who comes to baptism is possessed. The exorcism prayers are a warning to satan not to touch the person because he/she is becoming a Christian and will serve and worship only one Lord - Jesus Christ.
The owners of the slave-girl were not happy about losing their source of income, so they had Paul and Silas imprisoned. While in prison, they prayed and miraculously were freed. Instead of running away they stayed in the cell, and it was a good thing because they were able to prevent a suicide attempt by the jailer. As the jailer, he was responsible for all those imprisoned. If they escaped, he would have been tortured and possibly killed.
It seems that the jailer knew a least something about Paul and Silas because he took them outside, an action for which he also very likely would've been tortured and killed, and asked them about salvation, "What must I do to be saved?" This is significant because he was a Roman, meaning a pagan, and he was asking the men, whom he assumed to be Jews, for the way of salvation. His heart was already turned towards the One True God, he just needed instruction.
"They spoke the word of God to him and all who were in his house." They provided instruction not only to the jailer, but to his whole household, which included his family and, if any, slaves. And then all of them were baptized, they whole household. This has been the practice of the Church - to baptize after proper instruction (called catechism). Whether the person being baptized is an infant or an adult, or somewhere in-between, it is important that they make this great step fully realizing what they are doing and in Whose Name they are baptized, and what this will mean for the rest of their life.
Yours in the risen Lord,