Ghosts are one of the many signature symbols of Halloween, along with skeletons, carved pumpkins (jack-o-lanterns), and a general preoccupation with pain and death. The Bible does have something to say about ghosts and their relationship with Jesus' ministry.
The Old Testament in the King James translation uses the word "ghost(s)" ten times while the New Testament uses the word ninety-eight times! Most New Testament references are derived from the Greek word pneuma (Strong's Concordance #G4151) which roughly means "spirit." The KJV erroneously refers to God's spirit as the "holy ghost" (instead of the more correct "holy spirit") more than ninety times.
Surprisingly, one reference to this apparition involves Jesus' disciples using the word to describe him! This event occurred when Christ sent his disciples, in a boat, to the other side of the Sea of Galilee. Sometime in the middle of the night, after he was done praying, he noticed the disciples' boat was being tossed by the waves. He then proceeded to perform the incredible miracle of walking on water toward the ship! When the disciples saw him, they screamed in terror, "It's a ghost!" (Matthew 14:22 - 26).
Jesus and Demons
Christ, in Matthew 12, discussed a situation where a man had an unclean spirit (demon) leave him for a while. When the evil spirit could not find any place to go, he came back and found his "home" (the person he had possessed) empty and clean. This means the person did not fill the void left by the spirit with something that would keep him out (e.g. God's spirit). Not only did the demon possess the man again, seven of his evil friends came with him! This illustrates how serious a problem such "ghosts" can be.
But when the unclean spirit has departed from a man, it goes through dry places seeking rest, but finds none. Then it says, 'I will return to my house, from which I came out.' And after coming, it finds it unoccupied, swept and set in order.
Then it goes and takes with it seven other spirits more wicked than itself, and they enter in and dwell there; and the last state of that man is worse than the first. (Matthew 12:43 - 45, HBFV).
One day a father came to Jesus' disciples and asked them to cast an evil spirit ("ghost") out of his son. The demon was causing his child to throw himself into fire and water (Matthew 17:15). The spirit, however, required more faith than the disciples could muster in order to force him to leave. The father then went to Jesus who cast out the spirit.
"Lord, have mercy on my son, for he is insane and suffers miserably; for he often falls into the fire, and often into the water. And I brought him to Your disciples, but they were not able to heal him." . . .
Then the disciples came to Jesus privately and said, "Why were we not able to cast it out?" And Jesus said to them, "Because of your unbelief. For truly I say to you, if you have faith as a tiny mustard seed, you shall say to this mountain, 'Remove from here,' and it shall remove; and nothing shall be impossible to you. But this kind does not go out except by prayer and fasting." (Matthew 17:15 - 16, 19 - 21, HBFV).
What To Do
If you discover you have an unwanted spirit hanging around, find at least one or two others who are mature Christians (preferably with more faith than you possess). Get together with them and pray, in Jesus' name, that God remove the demon and have it never return. Depending on the type of demon, fasting and prayer may also be required to get rid of the spirit.
We, of our own power, cannot command demons (ghosts) to do anything. Jesus Christ, however, through his life and sacrifice, overcame all adversaries and nullified the works of the devil. His power, according to the Bible, can free you.