Is it Mental Illness or Demonic?

How do we determine when a manifestation of mental illness is psychological or demonic? Is such a determination even possible?

This is particularly pertinent in an urban context like ours, with an epidemic of mental illness on the streets. Sadly, it’s common to see disturbed individuals antagonizing commuters, hotly debating invisible foes, or muttering to themselves. Is this biological, spiritual, or both?

Interestingly, Jesus encountered all of these during His earthly ministry.

He regularly healed physical illnesses and disabilities—the tragic effects of a world groaning under sin (Romans 8:22)—including fevers, leprosy, paralysis, and even death (e.g., Mark 1:29–31; Matthew 8:1–2; 9:1–8; John 11:38–44). In most cases, these healings are attributed to the biological realm.

Jesus also regularly freed people from demonic oppression (Matthew 8:28–34; Luke 4:31–37)—a tragic effect of the powers of darkness (Ephesians 6:12). In these cases, such oppression is attributed to the spiritual realm.

Yet, at other times, physical disabilities are described as having demonic, not biological, origins. For example, the woman who could not “fully straighten herself” because she had a “disabling spirit” (Luke 13:10–17); the “demon-oppressed man who was mute” (Matthew 9:32–33); or the boy with an unclean spirit who foamed at the mouth and had seizures (Mark 9:17–27).

In other words, sometimes the problem was biological, sometimes it was spiritual, and at other times it was both. So, that said, how do we determine when a manifestation of mental illness is psychological or demonic? Let’s consider seven biblical observations.

#1 The Bible doesn’t give a clear answer.

This is an unsatisfying way to start. But there is a lesson here. God’s silence teaches. We can trust that when the Scriptures are silent on specific topics, God, in His wisdom, doesn’t see it as something we must know. Therefore, we must learn contentment within the boundaries He has drawn for us (Deuteronomy 29:29).

#2 We should avoid jumping to conclusions.

Since God hasn’t made it explicit, we should be cautious. The secular world usually finds cause purely in the biological realm. Meanwhile, the Church tends to find cause purely in the spiritual. The truth is often a mixture of the two. Demons are real. Mental illness is real. Discernment is required (Proverbs 18:17).

#3 Is the person a real Christian?

Demonic forces can’t possess a genuine Christian because the Spirit indwells them and, as such, are “God’s temple” (Romans 8:9; 1 Corinthians 3:16; 6:19; Galatians 4:6; Ephesians 1:13-14). Yet, a Christian can be influenced by demonic lies and sinful temptation (Ephesians 6:12). However, the situation is different for those who do not yet belong to Christ. Demons can possess them. Therefore, discerning the individual's spiritual state, whether in Christ or not, is crucial to charting a path forward.

#4 Has the person opened themselves to the demonic?

Has there been activity in their life that has invited evil? This may be evil they have chosen or evil that was forced upon them. For example, are they ensnared in a particular sin? Is there a history of participation in the occult or significant drug use? Have they been around others who have been demonized? This won’t be the sole determining factor, but it is a significant data point.

#5 Is there a legitimate medical issue?

Is there a physical or psychological diagnosis that adequately explains the symptoms? The Bible teaches that we are embodied souls—not mere souls nor mere bodies. Further, our bodies are part of creation that is “wasting away” and “subjected to frustration” (2 Corinthians 4:16; Romans 8:20). We will all experience this in varying degrees, ultimately so in death (Romans 6:23). Along the way, by God’s common grace, there are medicinal means of alleviating pain. Even Paul recommended Timothy take some wine “for the sake of [his] stomach and…frequent ailments” (1 Timothy 5:23).

#6 Are the symptoms rational or irrational?

Generally speaking, the demonic speak rationally (e.g., Genesis 3:1–5; Matthew 12:44), know things they shouldn’t (e.g., Acts 16:16–17; Mark 1:24), lie and deceive (John 8:44; 1 Timothy 4:1–2), prefer to remain hidden (2 Corinthians 11:14), and want to avoid Jesus (Matthew 8:29). Whereas those with more serious forms of mental illness are generally irrational, have ordinary knowledge, and may be quite open to Jesus. Again, discernment is required.

#7 Those in Christ are safe.

As we seek to help others, our primary attention should be on Him, not the demonic (Matthew 22:37–40). After all, their attention is on Him too—though not as it should be (James 2:19). He is our refuge (Psalm 46:1). We trust in the One who commands demonic legions with a word (Matthew 8:32) and provides spiritual armor to stand safely in Him (Ephesians 6:10–18). He has decisively “disarmed the rulers and authorities,” so we have nothing to fear (Colossians 2:15).

Pulling it all together

Given the layers involved, we won’t be able to tell all of this by walking past someone on the street. As a downtown church, we run into this all the time. When I see someone yelling or behaving unusually, my practice is to discern if there is any immediate help I can offer. If so, I do what I can. But usually, there is not much to do, so I pray:

Father, save that person. Jesus, rescue them from demonic influence, if there is any. Get them medical help and heal. Holy Spirit, right now, be their rescuer, their advocate, from the inside out. Be their shield of protection. Help, Lord, as only You can.

Then, trust the Lord knows and will do what is right.