We need to define “ghosts” before we attempt to answer your question. In the Bible the word “ghost” describes the “spirit” of a person. When a person dies, his “spirit” or “ghost” leaves his body. We can cite the example of the Lord Jesus to illustrate this. In Luke 23:45 we read, “And when Jesus had cried with a loud voice, He said, Father, into Thy hands I commend my SPIRIT: and having said thus, He gave up the GHOST.”

When people claim to have seen, felt or heard a ghost, they believe they have had contact with the spirit of a departed friend or loved one. But they are mistaken, for once a person dies his spirit cannot return to earth. This is clearly taught in the story of the “rich man and Lazarus” in Luke 16:19-31. After they died the spirit of the rich man was “in torments in Hades” (verse 23) and Lazarus was “carried by the angels to Abraham’s bosom” (verse 22) where he was “comforted” (verse 25). The rich man begged Abraham to send Lazarus to his father’s house on earth to warn his brothers of “this place of torment” (verse 28), but Abraham said, “They have Moses and the prophets; let them hear them” (verse 29). He went on to say, “If they do not hear Moses and the prophets, neither will they be persuaded though one rise from the dead” (verse 31). The implication is plain and simple; the spirit of one who had died is not allowed to return to earth to communicate with those who are still alive.

So, what “spirit” are people seeing, feeling or hearing? You mentioned “demonic spirits” in your question and I have no doubt that this is the spirit they are having contact with. One of the most graphic and disturbing examples of this in found in Mark chapter 5. In verse 1-2 we see that Jesus was met by “a man with an UNCLEAN SPIRIT (the words “unclean spirit” are used several times in Scripture to describe a “demonic spirit”). We aren’t told specifically that this man saw, felt or heard the unclean spirit, but we are told the horrific results of being possessed by it. He was DEPRESSED and SUICIDAL as we see in verse 5, “And always, night and day, he was in the mountains and in the tombs, CRYING OUT and CUTTING HIMSELF with stones.” People speak of being “haunted by ghosts”; this man was truly “haunted by demonic spirits!”

As to your question why some people experience these things, we can’t always be sure. In the case of the man with the unclean spirit in Mark 5, we aren’t told HOW it is that he became demon-possessed. Was he dabbling in the occult? If so, he was opening the door of his heart to evil spirits who eventually entered in and controlled him. Was he living in unjudged sin which opened him up to demonic influence? Judas Iscariot is a classic example of this, for he was a thief who was willing to betray the Lord Jesus for money and this led to Satan entering into him and controlling him (see Matthew 26:14-16, 21-25 and John 13:26-27). Or was as he an innocent victim, where an evil spirit was able to overcome him without any evil intentions on his part? There are cases in the Bible where children were possessed and it would seem they were innocent victims. One such case is found in Matthew 15:22, “And behold, a woman of Canaan came from that region and cried out to Him (Jesus), saying, ‘Have mercy on me, O Lord, Son of David! My daughter is severely demon-possessed’.” We see another example like this in Matthew 17:15 where a man came to Jesus and said, “Lord, have mercy on my son, for he is an epileptic and suffers severely; for he often falls into the fire and often into the water.” One may be thinking, “Nothing is said of him being controlled by demons?” Verse 18 goes on to tell us, “And Jesus REBUKED THE DEMON, and it came out of him; and the child was cured from the very hour.”

I personally believe the vast majority of cases of contacts with evil spirits is caused by either practicing the occult or living in unjudged sin, but we can’t rule out incidents where there are “innocent victims.” (289.9) (DO)