One of Paul's trips took him to Philippi where he and one of his traveling companion Silas a prophet, had an encounter with "a certain slave girl possessed with a spirit of divination met us, who brought her masters much profit by fortune-telling. This girl followed Paul and us, and cried out, saying, "These men are the servants of the Most High God, who proclaim to us the way of salvation." And this she did for many days. But Paul, greatly annoyed, turned and said to the spirit, "I command you in the name of Jesus Christ to come out of her." And he came out that very hour. (Acts 16:16-18)
Wow it sounded like free publicity for Paul. However, sometimes things may look or sound right, but believers are to discern what is going on and exercise their authority in the name of Jesus and demand that which is contrary to God’s will to come into alignment with it. This is exactly what happened here. Although this woman was speaking truth concerning Paul's mission, it was still the enemy that was trying to bring confusion to the Jews and Gentiles of Philippi.
The people of Philippi knew that this woman had a spirit of divination although what she was saying was true, Paul discerned what was going on, acted in faith, and used the authority in the name of Jesus to cast the spirit out. If he didn’t it would have appeared to the Jews that Paul was working with the wicked spirit and it would have appeared to the gentiles that there was no difference between the power of darkness and the power of God. This would have destroyed Paul's credibility as a true servant of Christ and would have squelched the gospel from having an effect.
I have met many Christians who think of the Name of Jesus as they do a good luck charm. They put more faith in a hand full of beads, a horoscope or a rabbit’s foot than in the name of Jesus. Their thinking is, “Well maybe it will work” or “Hopefully something good will happen”. But if your thinking is wrong, your believing will be wrong and if your believing is wrong then what you confess will also be wrong and it will be witnessed by your actions or inaction's.
The name of Jesus belongs to all believers and all believers have the right to use His name. When the devil or his gang tries anything, by faith any believer, even if they were saved today can command them to leave in the Name of Jesus and it must leave. PTL