Acts 16:16-18
As we were going to the place of prayer, we were met by a slave girl who had a spirit of divination and brought her owners much gain by fortune-telling. 17 She followed Paul and us, crying out, “These men are servants of the Most High God, who proclaim to you the way of salvation.” 18 And this she kept doing for many days. Paul, having become greatly annoyed, turned and said to the spirit, “I command you in the name of Jesus Christ to come out of her.” And it came out that very hour.
The pythoness
Luke actually writes that the slave girl had a "python spirit" because of her association with oracle giving. It is referred to the snake that guarded the temple of Ancient Greek God Apollo on Mount Parnassus.
The oracle at Delphi in Greece was reputedly guarded by a serpent or dragon, Apollo, in Greek mythology, killed the serpent and thus became the successor to the serpent's oracular power.
He was thought to be embodied in the snake and to inspire 'pythonesses' - female devotees with powers as mediums and clairvoyants.
She said, “These men are servants of the Most High God, who proclaim to you the way of salvation” indeed. Taking this fact in mind, what was Paul so annoyed about? Was he literally, annoyed with the slave girl?
The casting out
Paul was "deeply troubled." So Paul turned around and said to the spirit (not to the girl), "I command you in the name of Jesus Christ to come out of her!" The results are immediate.
"And it came out at that very moment"--this demon obeys the words of Paul. Here Luke is demonstrating Paul's authority over the fallen spirit world. What we have here are servants of the Most High God defeating the python spirit
This woman, this slave girl, brought a great deal of money to her owners because of her ability to tell fortunes. Paul took away her value. She was a commodity to her owners and Paul treated her the same way.
Paul saw what was wrong with the slave-girl, addressed the real issue, and allowed God to use him to set her free from demonic possession. That's what we should be doing, too.
Divination
Deuteronomy 18:10
There shall not be found among you anyone who burns his son or his daughter as an offering, anyone who practices divination or tells fortunes or interprets omens, or a sorcerer
Divination in any form is sin. It is not harmless entertainment or an alternate source of wisdom. Christians should avoid any practice related to divination, including fortune-telling, astrology, witchcraft, tarot cards, necromancy, and spell-casting.
Jeremiah 14:14
And the Lord said to me: “The prophets are prophesying lies in my name. I did not send them, nor did I command them or speak to them. They are prophesying to you a lying vision, worthless divination, and the deceit of their own minds.
Paul casting out a demon of divination