Paul at Philippi
On their second missionary journey, Paul and Silas came to a town called Philippi. While they were there, a certain woman followed them around saying, "These men are servants of the Most High God, which shows unto us the way of salvation."
This woman was saying words that sounded good, but she was possessed by a devil. She continued for many days to follow Paul around saying, "There men are servants of the Most High God, which show unto us the way of salvation."
Finally, Paul was grieved in his spirit and said to the woman, "I command thee in the name of Jesus Christ to come out of her." The demon came out that same hour, and the woman was set free.
How did Paul know that this woman was possessed by a devil? She was saying good words. Paul knew through the discerning of spirits. The Bible says that his spirit was grieved. One way that the discerning of spirits operates is through an inward witness—your spirit will become grieved.
Excerpt permission granted by Mark Harper Ministries