Demon possession is real. That alone should prove there is an invisible spirit realm around us, but much more when a person notices that demon spirits are driven out in the name of the Lord Jesus Christ. The Acts 16:18 passage is explicit showing how the Apostle Paul did that very thing:
She kept this up for many days. Finally Paul became so troubled that he turned around and said to the spirit, “In the name of Jesus Christ I command you to come out of her!” At that moment the spirit left her.
Very encouraging is Mark 5:12,13. It shows 2,000 demons begging Jesus before they were driven from inside a man they had horribly tormented:
The demons begged Jesus, “Send us among the pigs; allow us to go into them.” He gave them permission, andthe evil spirits came out and went into the pigs. The herd, about two thousand in number, rushed down the steep bank into the lake and were drowned. (Mark 5:12,13)
NOTE: Animals can even become demon possessed, according to that! Other Scriptures show that young children can also be demon possessed! How a little child could be afflicted in that manner is not clear, but it is still factual, for it does occur, but there is hope in God through the Lord Jesus Christ:
Jesus asked the boy’s father, “How long has he been like this?” “From childhood,” he answered. (Mark 9:21)
The Greek word translated childhood there means infancy! Jesus came to the rescue again as the passage goes on to read. Do you know that one and only Savior of mankind? If not, repent and place a submissive faith in him to unashamedly follow and serve him. This is a heaven or hell issue. GOD BLESS YOU.