In John 20:22, (New King James Version) we read, And when he had said this, he breathed on them, and saith unto them, Receive ye the Holy Ghost.Of the 96 references to ghosts in the New Testament 88 refer to this Holy Ghost, that is, the Holy Spirit from God; the other 8 instances refer to when Jesus and a few others died - gave up the ghost, as in John 19:30, When Jesus therefore had received the vinegar, he said, It is finished: and he bowed his head, and gave up the ghost. On the other hand, popular culture characterizes a ghost as the supposed spirit of somebody who has died, believed to appear as a shadowy form, causing sounds, the movement of objects, or a frightening atmosphere in a place. Descriptions of the apparition of ghosts vary widely; the mode of manifestation can range from an invisible presence to translucent or wispy shapes, to realistic, life-like visions.
But the bible does not say anything about ghosts lingering on earth and frightening the daylights out of people. Indeed, Jesus said to the man who was about to die on the cross, “Today you shall be with me in Paradise." (Luke 23:43).Jesus said so because He of course knew that It is appointed onto man once to die, and after that, the judgment (Heb 9:27). There is no roaming around after death looking for God knows what. The teaching by some Christian denominations that ghosts are beings who linger in an interim state after death and before continuing their journey to heaven is proved very wrong by scriptures.
The Old testament does contains a few references to ghosts, associating spiritism and all paranormal activities with forbidden occult activities, as in Deut 18:11. The deliberate attempt to contact the spirit of a deceased person is known as necromancy, or in spiritism as a séance. And the bible roundly condemns that practice. So he said to her, “What is his form?” And she said, “An old man is coming up, and he is covered with a mantle.” And Saul perceived that it was Samuel, and he stooped with his face to the ground and bowed down. Now Samuel said to Saul, “Why have you disturbed me by bringing me up?” And Saul answered, “I am deeply distressed; for the Philistines make war against me, and God has departed from me and does not answer me anymore, neither by prophets nor by dreams. Therefore I have called you, that you may reveal to me what I should do.” Then Samuel said: “So why do you ask me, seeing the Lord has departed from you and has become your enemy? And the Lord has done for Himself as He spoke by me. For the Lord has torn the kingdom out of your hand and given it to your neighbor, David. Because you did not obey the voice of the Lord nor execute His fierce wrath upon Amalek, therefore the Lord has done this thing to you this day. Moreover the Lord will also deliver Israel with you into the hand of the Philistines. And tomorrow you and your sons will be with me. The Lord will also deliver the army of Israel into the hand of the Philistines." (I Sam 28: 5-8).
Because a lot of people, even in the church, believe in such ghosts and apparitions, Jesus, following the resurrection had to persuade the disciples that he was not a ghost, in Luke 24:37-39. Mt 14:26 shows that even earlier, Jesus' followers at first believed him to be a ghost (spirit) when He walked on water, but He quickly set them staright.
So, what is it that people see? Apparitions and orbs of light are explained by 2 Cor 11:14, even Satan disguises himself as an angel of light. Some so-called ghosts are actually said to be demons, unclean spirits who, according to 1 Timothy 4:1, come to deceive people and draw them away from God and into bondage. As a result, attempts to contact the dead will very likely lead to unwanted contact with a demon or an unclean spirit.
Who are these people who see apparitions? In 1 Sam 28:15-16, the bible says that those who see 'ghosts' are like this; The Lord had left him.
What should they do? Connect, or reconnect with Jesus, who will give them the Holy Spirit, who will then start to teach and guide them, so that they do not need to go to the dead for guidance, However, when He, the Spirit of truth, has come, He will guide you into all truth; for He will not speak on His own authority, but whatever He hears He will speak; and He will tell you things to come(John 16:13).