What does the Bible say about demons?

Demons in the Bible are not the red-horned creatures of medieval art. They are spiritual beings opposed to God who afflict human beings with physical, mental, and spiritual harm. The Old Testament says relatively little about them; the New Testament, especially the Gospels, says much more.

This guide examines what the Bible actually teaches about demons, how Jesus dealt with them, and what their existence means for believers today.

The Old Testament mentions demons only in passing. Deuteronomy 32:17 says Israel "sacrificed unto devils, not to God." Leviticus 17:7 prohibits sacrificing to "devils." Psalm 106:37 records that they sacrificed their children to "devils." The Hebrew words suggest pagan deities or hostile spiritual beings.

The Old Testament’s relative silence about demons reflects its overwhelming emphasis on God’s sovereignty. Evil exists, but God is in control. There is no cosmic dualism in the Hebrew Bible: Satan in Job is an accuser operating under God’s permission, not an independent power.

The Gospels describe numerous encounters between Jesus and demons. He cast them out with a word. They recognised him and feared him. The most dramatic account is the Gadarene demoniac, where a legion of demons begged Jesus to send them into a herd of swine rather than into the abyss.

Jesus gave his disciples authority to cast out demons as well. This authority was a sign that the kingdom of God had arrived: "If I cast out devils by the Spirit of God, then the kingdom of God is come unto you." Demon expulsion was not peripheral to Jesus’s ministry; it was central evidence of his messianic mission.

Paul warned that believers wrestle "not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world." James said, "Resist the devil, and he will flee from you." Peter compared the devil to a roaring lion seeking whom he may devour.

The Bible treats demons as real but defeated. Christ’s death and resurrection broke their power. Believers are told to resist, not to fear. The focus is always on God’s greater power, not on demonic capability. The Bible spends far more time describing God’s love than the devil’s schemes.