Demons & Unclean Spirits

What Are Demons?

Here is a puzzle worth sitting with: the Old Testament rarely describes demons the way the New Testament does — yet the moment we open the Gospels, they are everywhere. They speak. They recognize Jesus. They possess people. They fear judgment. They obey Christ.

And notice what never happens. Nobody stops to ask, “What is a demon?” Matthew, Mark, Luke, and John do not explain it. Why not? Because the original audience already had a worldview for understanding these beings. To read the Gospels the way their first readers did, we have to step briefly into that world.

The world between the Testaments

The stretch from the rebuilding of the Temple after the exile (around 516 BC) to its destruction in AD 70 is called the Second Temple period. It is the world Jesus lived in, the world of the apostles and the Pharisees, and the world in which the Gospels were written. During these centuries Jewish writers wrestled with hard Old Testament passages and developed traditions to explain them — writings such as 1 Enoch, Jubilees, and the Dead Sea Scrolls.

So where did they think demons came from?

Many Christians answer quickly: “They’re fallen angels.” That has been a common teaching — but it is not how most Jews in Jesus’ day understood it. They traced the origin of demons back to Genesis 6.

Pastor Frank walked through this passage back in Week 2, so today we are not re-asking “who were the sons of God?” We are asking a different question — one Genesis never directly answers: what happened after the Nephilim died?

The Second Temple answer

The dominant Jewish reading ran like this. The sons of God were heavenly beings; humans were earthly beings; the Nephilim were the unnatural offspring of that union. When the Flood came, their bodies perished — but their spirits belonged nowhere. Not to God’s heavenly family. Not to humanity. And so, in this understanding, they became wandering, disembodied spirits, seeking a body to inhabit and influence. Those spirits are what the New Testament calls demons, evil spirits, unclean spirits.

This is why the Gospels repeatedly show demons seeking a body rather than ruling territory the way the national powers of Week 3 did. It also draws several threads together: the rebellion of Genesis 6, and the Rephaim — the dead giant clans associated with the realm of the dead (Isaiah 14:9) — whose shadowy afterlife reinforced the link between the giants and roaming evil spirits.

Why Are They Called “Unclean Spirits”?

One of the quiet surprises of the Gospels is that Jesus and the Gospel writers rarely say “demon.” Far more often they use another phrase: unclean spirit — in Greek, pneuma akatharton. That word choice is not accidental.

What “unclean” actually means

In the Bible, uncleanness is much more than physical dirt. It names anything incompatible with the holiness of God. The Law taught Israel to distinguish the holy, the common, the clean, and the unclean — constant reminders that sin, death, corruption, and idolatry cannot stand in God’s presence. Demons are called unclean because everything they represent stands opposed to God’s holiness.

• They are associated with death. Death is one of Scripture’s great sources of uncleanness — and the Second Temple view tied demons to the spirits of the dead Nephilim. That is why first-century Jews naturally linked them with impurity and corruption.
• They corrupt what God made good. Demons never create; they only distort — minds, bodies, worship, truth, relationships, nations. Satan’s kingdom always warps what God designed.
• They oppose God’s presence. As uncleanness once barred a person from the sanctuary, unclean spirits work to keep people in bondage rather than fellowship with God.

Jesus never becomes unclean

Under the Law, touching a leper or a corpse made a person ceremonially unclean. Yet Jesus repeatedly touched lepers, the dead, the sick, the demonized — and something astonishing kept happening. He never became unclean. Instead, the unclean became clean. The leper was healed, the dead were raised, the demonized were delivered. The direction of holiness had reversed: instead of impurity spreading to Jesus, the holiness of Jesus overwhelmed impurity. That reversal is a sign that the Kingdom of God had arrived.

Why this scene is so striking

The religious leaders questioned who Jesus was. The crowds debated it. Even the disciples came to it slowly. But the demon knew immediately — “the Holy One of God.” As James would later put it, “even the demons believe—and shudder” (James 2:19). Their problem was never ignorance; it was rebellion. And notice the fear in the question “Have you come to destroy us?” — they know they are already defeated. Their only uncertainty is the timing.

Notice too that Jesus performs no ritual. Jewish and pagan exorcists relied on formulas, sacred objects, incantations, the invoking of higher names. Jesus simply says, “Be silent, and come out” — and it obeys. This is not borrowed power. It is His own divine authority as the Son of God, and the crowd feels it at once.

Jesus’ Authority Over Demons

Jesus’ deliverance ministry was never simply about helping individuals. Every encounter with a demon was a public declaration: the Kingdom of God has arrived, and the kingdom of darkness is being overthrown.

The man called Legion

Jesus crosses the Sea of Galilee, and the moment He steps out of the boat a man overwhelmed by many demons runs toward Him. No chain could hold this man; he lived among the tombs, his life completely dominated by the kingdom of darkness. When Jesus asks the spirit its name, the answer is chilling: Legion — the word for a Roman army division of several thousand — “for we are many.”

Four things this teaches about demons

• They recognize authority. No introductions, no debate — the King has arrived, and they know it instantly.
• They fear judgment. Matthew’s account adds the tell: “Have you come here to torment us before the time?” (Matthew 8:29). They know there is an appointed day, that Jesus has authority to judge them, and that their defeat is certain. Their dread is only that it has come early.
• They require permission. They cannot simply do as they please — they must ask to enter the pigs, and Jesus grants it. Just as Satan could not touch Job apart from God’s permission, neither can these spirits act on their own.
• They desire embodiment. They do not ask to vanish; they ask to enter another living host. This is exactly what the Second Temple worldview would expect — disembodied spirits seeking a body — and it is why Heiser says stories like Legion read so naturally through first-century eyes.

Why cast out so many?

It is tempting to say Jesus simply felt compassion — and He did — but something larger is happening. Every exorcism is an announcement.

Picture an invading king marching into occupied territory. Every city he liberates raises his banner; every fortress he takes announces that a new king now rules. That is what Jesus is doing. Every demon expelled proclaims the same thing: the true King has arrived.

The Victory of Christ Over Demons

Christ did not only confront the darkness — He defeated it. Which means believers do not minister from fear, but from a finished work.

More than deliverance

Jesus cast out many demons, but He did not come merely to cast out demons — He came to establish the Kingdom of God. Every deliverance was a visible sign that Satan’s kingdom was being overthrown, and more than that: Jesus was not simply removing demons from people, He was reclaiming people for God.

The cross disarmed the powers

The cross was not only about forgiving sins; it was God’s public triumph over every rebellious power — the very rulers and authorities we met in Week 3.

The Greek word for disarmed pictures stripping the weapons and armor from a defeated army and marching its leaders through the streets. That is Paul’s image of Calvary. The event Satan thought would destroy Jesus became the means of his own defeat.

He shares the authority — and reorders the joy

Jesus did not keep His authority to Himself; He entrusted His mission to His followers. When the seventy-two return thrilled that “even the demons are subject to us in your name,” Jesus gently redirects them.

The authority is real. But our relationship with Jesus is greater than any power over demons — and that ordering is a safeguard. It keeps the Church from becoming fascinated with power while neglecting the One who gives it.

Where it all lands

Four weeks — the Divine Council, the Three Rebellions, Satan and the Powers, and now Demons and Unclean Spirits — and none of it was so that we would become experts on darkness or afraid of the enemy. It was so we would see one greater truth: the kingdom of darkness is real, but it is not ultimate. Christ is.

Key Terms

• Second Temple period — roughly 516 BC to AD 70; the world of Jesus, the apostles, and the writing of the Gospels — and the interpretive world assumed behind them.
• 1 Enoch / Jubilees / Dead Sea Scrolls — Second Temple Jewish writings that preserve the demon-origin tradition. Valuable background — never Scripture, never doctrine.
• Nephilim — the offspring of the “sons of God” and human women in Genesis 6; in the Second Temple view, their disembodied spirits became the demons of the Gospels.
• Rephaim — the dead giant clans associated with the realm of the dead (Isaiah 14:9); their shadowy afterlife reinforced the link between the giants and roaming evil spirits.
• Unclean spirit (pneuma akatharton) — the Gospels’ preferred term for a demon; “unclean” means opposed to God’s holiness, tied to death and corruption — not mere dirt.
• Daimonion — the Greek word “demon,” used far less often in the Gospel narratives than “unclean spirit.”
• Legion — the name the many demons give in Mark 5; a Roman legion numbered several thousand soldiers.
• Disarmed (Colossians 2:15) — the Greek pictures stripping weapons and armor from a defeated army; Paul’s image of what the cross did to the powers.

Reflection & Discussion

1. The Gospel writers never stop to define “demon” — they assume their readers already know. How does understanding their first-century worldview change the way you read the Gospels?
2. Why does it matter to flag honestly that the Nephilim-spirit origin of demons is Second Temple background the New Testament assumes, rather than a verse Genesis states outright? What does that kind of care protect us from?
3. “Unclean” means opposed to God’s holiness, not merely dirty. Where do you see the enemy’s pattern of corrupting good things God made — in minds, worship, relationships — rather than creating anything new?
4. With lepers, the dead, and the demonized, holiness flowed from Jesus rather than impurity flowing to Him. Where do you need His cleansing to overwhelm something you thought was too far gone?
5. The demons of Legion knew exactly who Jesus was, yet remained in rebellion. What’s the difference between believing true things about Jesus and actually submitting to Him?
6. “Have you come to torment us before the time?” is a confession that their defeat is already certain. How would this week look different if you lived as though the enemy is already a defeated foe?
7. The disciples were thrilled that demons obeyed them; Jesus redirected their joy to their names written in heaven. Why is it dangerous to be more fascinated with spiritual power than with belonging to Christ?
8. Jesus never glorified demons or held long conversations with them — He simply commanded them. What does that model teach us about a healthy, Christ-centered approach to spiritual warfare?
9. Colossians 2:15 says the cross disarmed the powers. What weapon — a fear, an accusation, a lie — is the enemy still waving at you that Christ has already stripped from his hand?
10. Four weeks in, the point was never to become experts on darkness but to see the greatness of Christ. What has this study changed about how big Jesus is to you?

Week 5 — Angels: The Loyal Host

Four weeks on the rebels — now we meet the servants who kept their post. Next week we empty the greeting-card category and let Scripture rebuild it: what “angel” actually means, how heaven’s ordered household works, the throne guardians the prophets saw — and the one Angel who breaks every rule, because He is Yahweh made visible.