What are ghosts?
Question: What are ghosts? Are they the spirits of dead people trapped between this world and the next?
Answer: "Ghosts" are not the spirits of dead people trapped between this world and the next. Hebrews 9:27 says, "And as it is appointed unto men once to die, but after this the judgment." Second Corinthians 5:8 says (for the Christian) to be absent from the body is to be present with the Lord. There is no "in-between" state where a spirit is trapped. So how do we explain "ghosts"?
First, some ghosts can be explained through an overly-active imagination. If people think their house is haunted, they will imagine that they see and hear things. It's nothing more than imaginations.
Second, some ghosts can be explained through natural phenomenon. The house settling (creaking), the air conditioning and heating ducts expanding and contracting, shadows coming through the windows, mice in the attic, wind blowing, etc.
Third, some ghost are demons which impersonate dead people. These demons are called "deceitful spirits" because of their ability to convince people that they are disembodied spirits of dead people, rather than what they really are-fallen angels. First Timothy 4:1 says some people will fall away from the faith because they have been listening to deceitful spirits. They are trying to lead people away from the truth, who is Jesus Christ.
These demons that imitate dead people are also called "familiar spirits" in the Bible, probably because they were familiar with the deceased person and can imitate his or her voice. Spirit mediums claim they can channel the deceased person's voice to give messages from the "other side." In most cases, the medium fakes the person's voice. However in a few rare cases, it is a demon and not the deceased person who is speaking through the medium.
For example, a demon that was familiar with a person living in the 1800's can give accurate information about the deceased individual. It will pretend to be the deceased person's spirit, but it is actually a demon. The Bible warns us about trying to contact the dead because it opens the door to demons.
Leviticus 20:6 says, "And the soul that turns after such as have familiar spirits…I will even set my face against that soul, and will cut him off from among his people."
Isaiah 8:19 "And when they shall say unto you, Seek unto them that have familiar spirits, and unto wizards that peep, and that mutter: should not a people seek unto their God?"
Saul died because he transgressed against the Lord for asking counsel of one that had a familiar spirit, to inquire of it (1 Chronicles 10:13).
Christians should never be afraid of "ghosts," which are actually demons, because "greater is He who is in you than he who is in the world" (1 John 4:4).