Ghost, Real Ghost, Scary Ghost, Do Ghosts Exist, Videos of GhostsThe spirits or ghosts is completely non physical although they can take on a physical appearance that will be in every way the same as a normal human being for example. As regards the functions of spirits in the world, and their active relations to the visible order of things, it must be understood that most encounters with spirits will be evil. In Theology, the uses of the word are various. In the New Testament, it signifies sometimes the soul of man (generally its highest part, e.g., "the spirit is willing"), sometimes the supernatural action of God in man, sometimes the Holy Ghost ("the Spirit of Truth Whom the world cannot receive"). The use of this term to signify the supernatural life of grace is the explanation of St. Paul's language about the spiritual and the carnal man and his enumeration of the three elements, spirit, soul, and body, which gave occasion to the error of the Trichotomists (1 Thessalonians 5:23, Ephesians 4:23).
St. Thomas teaches the complete simplicity of all spiritual natures. The spirits or ghosts is completely non physical although they can take on a physical appearance that will be in every way the same as a normal human being for example. As regards the functions of spirits in the world, and their active relations to the visible order of things, it must be understood that most encounters with spirits will be evil. But there are also good spiritual messengers (angels) and Scripture abounds in instances of their dealings with men, chiefly in the character of intermediaries between God and His servants. They are the heralds who announce his commands, and often too the ministers who execute His justice. They take a benevolent interest in the spiritual good of men (Luke 15:10). For these reasons, the Church permits and encourages devotion to the angels. However, if you as a person should be contacted of a spirit or someone you know should be so, it is extremely important that you try to ignore the Spirit as much as you are able and that you directly tries to Pray Holy Prayers of different sorts in order to frighten the evil spirit. Not all, but the overwhelming majority will be evil spirits trying to communicate with you. Beware and stay away from mortal sins, and you will generally be safe.
In Christian terminology, a ghost is the soul or spirit of a deceased person, taken to be capable of appearing in visible form or otherwise manifesting itself to the living. Descriptions of ghosts vary very much: the specific way of manifestation can vary from an invisible presence to translucent or wispy shapes, to realistic, life-like visions that attack, hurt or even kill human beings. The deliberate attempt to contact the spirit of a deceased person by way of occult means is known as necromancy, or in spiritism as a séance, and is strictly forbidden in Christianity under pain of death.
Humanity have believed in the presence of spirits or ghosts of different kinds from the very beginning. Ghosts are generally described as solitary essences that haunt particular locations, objects, or people with which they were associated in life, though stories of phantom armies, ghost trains, phantom ships, and even ghost animals have also been recounted. Mostly, it is very difficult to distinguish if the ghost that is manifesting is good or evil. The Catholic belief has always been that it is gravely and motally sinful to contact these ghosts or spirits by way of occult means, but that those of the faithful who died as a member of the Church could be prayed for.
The Bible contain few references to ghosts, but there are a few noteworthy ones. The most notable reference is in the First Book of Samuel (I Samuel 28:3-19), in which a disguised King Saul has the Witch of Endor summon the Ghost of Samuel. This horrible deed by Saul was punished with capital punishment during the Old Testament time and through the Middle Ages until when recently it sadly became allowed:
 Now Samuel was dead, and all Israel mourned for him, and buried him in Ramatha his city. And Saul had put away all the magicians and soothsayers out of the land.  And the Philistines were gathered together, and came and camped in Sunam: and Saul also gathered together all Israel, and came to Gelboe.  And Saul saw the army of the Plilistines, and was afraid, and his heart was very much dismayed.  And he consulted the Lord, and he answered him not, neither by dreams, nor by priests, nor by prophets.  And Saul said to his servants: Seek me a woman that hath a divining spirit, and I will go to her, and inquire by her. And his servants said to him: There is a woman that hath a divining spirit at Endor.  Then he disguised himself: and put on other clothes, and he went, and two men with him, and they came to the woman by night, and he said to her: Divine to me by thy divining spirit, and bring me up him whom I shall tell thee.  And the woman said to him: Behold thou knowest all that Saul hath done, and how he hath rooted out the magicians and soothsayers from the land: why then dost thou lay a snare for my life, to cause me to be put to death?  And Saul swore unto her by the Lord, saying: As the Lord liveth there shall no evil happen to thee for this thing.
 And the woman said to him: Whom shall I bring up to thee? And he said, Bring me up Samuel.  And when the woman saw Samuel, she cried out with a loud voice, and said to Saul: Why hast thou deceived me? for thou art Saul.  And the king said to her: Fear not: what hast thou seen? And the woman said to Saul: I saw gods ascending out of the earth.  And he said to her: What form is he of? And she said: An old man cometh up, and he is covered with a mantle. And Saul understood that it was Samuel, and he bowed himself with his face to the ground, and adored.  And Samuel said to Saul: Why hast thou disturbed my rest, that I should be brought up? And Saul said, I am in great distress: for the Philistines fight against me, and God is departed from me, and would not hear me, neither by the hand of prophets, nor by dreams: therefore I have called thee, that thou mayest shew me what I shall do.
 "Understood that it was Samuel"... It is the more common opinion of the holy fathers, and interpreters, that the soul of Samuel appeared indeed: and not, as some have imagined, an evil spirit in his shape. Not that the power of her magic could bring him thither, but that God was pleased for the punishment of Saul, that Samuel himself should denounce unto him the evils that were falling upon him. See Eccli. 46. 23.
 And Samuel said: Why askest thou me, seeing the Lord has departed from thee, and is gone over to thy rival:  For the Lord will do to thee as he spoke by me, and he will rend thy kingdom out of thy hand, and will give it to thy neighbour David:  Because thou didst not obey the voice of the Lord, neither didst thou execute the wrath of his indignation upon Amalec. Therefore hath the Lord done to thee what thou sufferest this day.  And the Lord also will deliver Israel with thee into the hands of the Philistines: and tomorrow thou and thy sons shall be with me: and the Lord will also deliver the army of Israel into the hands of the Philistines.  And forthwith Saul fell all along on the ground, for he was frightened with the words of Samuel, and there was no strength in him, for he had eaten no bread all that day.
 "With me"... That is, in the state of the dead, and in another world, though not in the same place.
In the New Testament, Jesus has to persuade the Disciples that he is not a ghost following the resurrection, Luke 24:37-39.Likewise, Jesus' Apostles at first believe him to be a ghost when they see him walking on water.
The Christian Church considers ghosts as beings who though they appear on the earth, no longer live on the material plane. On occasion, God would allow the souls in this state to return to earth to warn the living of the need for repentance and give them good advice how they should amend their ways. One example of deceased persons appearing in the New Testament is when Jesus speaks with Elia and Moses on the Mountain, and this shows that it not always evil or sinful to speak with a deceased person's spirit or ghost. Nevertheless, Christians are taught that it is sinful to attempt to conjure or control spirits by way of occult means in accordance with Deuteronomy XVIII: 9–12.
Most of the ghosts are actually demons in disguise, who the Church teaches, in accordance with I Timothy 4:1, that they "come to deceive people and draw them away from God and into bondage."As a result, attempts to contact the dead in an occult way may lead to unwanted contact with a demon or an unclean spirit.
According to Christian belief, appearances of orbs of light, a common paranormal phenomenon attributed to ghosts, can be explained by II Corinthians 11:14, which states that "even Satan disguises himself as an angel of light." If you should happen to see a ghost of any kind, it is much more probable that it is a fallen angel (demon) or an evil spirit which comes for the express purpose of deceiving you in any way. Therefore, when such a thing happens, do not pay too much heed to the Spirit or Ghost, but turn your mind to Our Lord, and ask him to protect you if this is an evil being that is trying to deceive you. Try to ignore it as much as you can, and use Holy Prayers in order to protect yourself. May God be with you all. Amen