Medium can mean a number of different things, but in the supernatural world, a medium is someone who serves to relay messages coming from spirits. Thus, medium is a connection between spirit world and world of humans. The bible mentions practice of medium, but this act was condemned in the text as it was main practice in order to speak to the dead.
Mediums are also called channelers. This term arose from the fact that such people make communication between the living and the dead possible. There specific mediums who can only communicate with certain forms of spirits, whereas others have more diverse supernatural communications. Messages relayed through mediums may be in the form of visuals, sound messages, or physical sensations. Mediums are not the same as psychics, which are individuals who read “energies” emanating from people or locations. Psychics do not in anyway, communicate with entities from the spiritual world. Mediums need not be witches, wizards, necromancers, or sorcerers as their ability to communicate with spirits is inherited.
As mentioned, the bible mentions about mediums in some of its chapters. For instance, Leviticus 20:27 cites condemnation of mediums, whereas Deuteronomy 18:10–11 mentions other supernatural practitioners, including wizards, witches, and sorcerers.
As described in 1 Samuel 28, King Saul thought that it was a sin to seek the help of mediums. However, when God failed to answer his prayers after the prophet Samuel died, he then asked his followers to find a medium for him. Through the hired medium, King Saul was able to communicate with the dead soul of the prophet. The apparition revealed some undesirable predictions, and the king died the day after.
Several passages in the New Testament also describe sorcery and other practices as sinful activities that are meant for communicating with spirits.
It should also be clarified that mediums do not conjure spirits of the deceased. One example is story in Luke 16:18–31, wherein Jesus mentions the story of a rich man and Lazarus. Meanwhile, some spirits are outright liars who communicate with mediums just to fool people into believing that they are communicating with their loved ones. This is especially true in instances when grieving parents try to find ways to talk with their dead children again. There’s a possibility that they will encounter a demon instead; such evil entities normally assume the form of dead humans in order to deceive people.