Necromancy is the ninth and last occult practice listed in Deuteronomy 18:9-12, rendered "one who calls up the dead" in the New King James and "necromancer" in the King James. The necromancer claims to consult the dead, investigating and seeking information from them. The phrase occurs only in Deuteronomy 18:11. God calls every practice in that list an abomination, and the necromancer falls under that verdict. Necromancy is a kind of sorcery, and the medium, the spiritist, and the necromancer are three ways of describing one practice: consulting evil spirits. Mediums profess to call up the departed from the realm of the dead, and they may use ventriloquism to deceive, as Isaiah 8:19 and 29:4 suggest. Isaiah asks whether people should seek the dead on behalf of the living, and directs them instead to the law and the testimony. The woman of Endor, who conducted a séance to bring up Samuel for Saul in I Samuel 28, is never called a witch in the biblical text. She is a necromancer, one who specifically consults the spirits of the dead to predict the future. Necromancy is idolatry and sin, and Satan, the father of lies, stands behind it. It is deception and a counterfeit of miracles, and it leads to judgment unless there is repentance. Christians must not learn or become accustomed to it.

Necromancy cannot actually contact the dead. The dead know nothing and are unconscious until the resurrection (Ecclesiastes 9:5, 10), since humans are mortal and the soul does not live on apart from the body (Ezekiel 18:4; Matthew 10:28). God condemns all occult practice, including consulting mediums and necromancers (Leviticus 19:31; 20:6; Deuteronomy 18:9-14), and sorcerers will be cast into the Lake of Fire (Revelation 21:8). Behind such practices stand demons, who deceive by appearing attractive, even as ministers of righteousness (II Corinthians 11:14-15). Saul's visit to the medium at En Dor (I Samuel 28) does not prove that necromancy works. Samuel had been dead about five years, and God had refused to answer Saul. The medium was a fraud who never truly contacted the dead, and the apparition shocked her. She only thought she saw Samuel; she described a spirit ascending out of the earth, which marks a demon rather than a messenger from heaven, and she saw elohim with a plural verb, which indicates pagan gods. Saul himself saw nothing, and her vague details of an old man in a mantle were enough to convince him, because he was desperate and emotionally unstable. God would never answer through a lying spirit in an abominable séance. At most He allowed a demon to impersonate Samuel and pronounce Saul's doom, which broke the king utterly. The story warns that forsaking God for the counsel of demons leads to fear, despair, lies, and death.

Necromancy surfaces directly in Deuteronomy 18:9-14, where God warns Israel not to learn the detestable practices of the nations they are about to dispossess, listing witchcraft, soothsaying, interpreting omens, sorcery, conjuring spells, mediums, spiritists, and "one who calls up the dead"—a necromancer. God calls all who do these things an abomination and states that it is precisely because of such practices that He drove the previous nations out of the land. Israel is commanded instead to be blameless before Him, trusting His revelation rather than seeking guidance through the dead. This practice is rooted historically in the Celtic festival of Samhain, the origin of Halloween. The Celts believed that during the three days surrounding November 1, the veil between the physical and spirit worlds relaxed, allowing the dead to cross into the living world and, conversely, allowing the living to cross over and contact their departed ancestors through divination, incantation, potion, or meditation. Druids and Bards specifically sought inspiration from the spirit world in this way, believing it improved their poetry and guidance. This practice of consulting or "calling up" the dead for knowledge or inspiration is the essence of necromancy, and it survives as one of the underlying spiritistic elements still embedded in modern Halloween observance, even though the holiday is often presented as harmless fun. The broader biblical teaching places necromancy within the "holiness code" of Leviticus 19 and 20, where mediums and familiar spirits are forbidden, and God commands, "Give no regard to mediums and familiar spirits; do not seek after them... I am the LORD your God." Those who turn after such spirits are said to "prostitute" themselves, and God declares He will "set His face against" them and cut them off from His people. Necromancy and related spiritistic practices are thus equated with spiritual prostitution—idolatry in another form—and are punishable by death under the Old Covenant, just as adultery and idolatry were. Exodus 22:16-20 groups sorcery directly between sexual sin and idolatry, showing that God ranks consulting spirits, including the dead, alongside the gravest violations of covenant loyalty. I Samuel 15:22-23 deepens this connection by declaring that "rebellion is as the sin of witchcraft," tying necromancy and sorcery to the broader principle of rejecting God's word. Any attempt to gain knowledge, comfort, or guidance from the dead rather than from God constitutes disobedience and rebellion, driving a wedge between the believer and God much as adultery severs a marriage. The New Testament confirms this continuity: Galatians 5:19-21 lists sorcery among the works of the flesh that exclude one from inheriting God's Kingdom, following the same sequence of sexual sin, idolatry, and sorcery found in the Old Testament. Paul's use of the term pharmakeia reflects the ancient use of drugs by sorcerers and mediums to induce trance states for contacting spirits, a practice still echoed in Halloween's darker, drug-associated rituals. Ultimately, necromancy is presented as one expression of spiritism that defiles both the individual and the land, separates people from God, and invites judgment. The call throughout is to reject any inquiry into the practices of calling up the dead, to remain pure and holy, and to walk instead as children of light rather than participating in the darkness that Halloween, through its Samhain roots, still perpetuates.