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Can Demons Cause Mental Illness?

July 25, 2013 by  
Filed under Demonology, Fr. Fortea

Dear Fr. Fortea, can a demon cause a mental illness in a person?

Demons can tempt us, and they sometimes do so in a continuous way with great intensity. As such, a demon could provoke an obsession, phobia, depression, or another type of mental illness in a person. This Gargoyle_13 Wikimediacan seriously disturb a person’s ordinary life to the point of making him unbalanced. So, yes, a demon can cause mental illness – but only if God permits it. (Of course, everything that occurs must either be willed or at least permitted by God.)

Given the internal mechanism that is used to cause temptation – that is, the infusion of a thought or image in our intellect, memory, or imagination – this modus operandi can be used in such a pernicious way that it can unbalance a person. This is well within the power of a demon. The only thing that can prevent this activity is the will of God. So does God always prevent demons from causing a mental illness in a person? Undoubtedly, no. But this is the exception, not the rule. In most cases, mental illnesses have purely natural causes.


Editor's Note: To learn more about spiritual warfare and demonology, Catholic Spiritual Direction recommends Fr. Fortea’s excellent book, Interview With An Exorcist – An Insider’s Look at the Devil, Demonic Possession, and the Path to Deliverance.


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About Fr. Jose Antonio Fortea

Father José Antonio Fortea is not only an exorcist, but also a writer, and parish priest. He once thought he would lead what he has termed ordinary life as an attorney in Madrid, much as his father did before him, but sensed instead a vocation to the priesthood in his adolescent years. A theology graduate of Navarre University in Spain, Father Fortea wrote a thesis there on exorcism. He has been a practicing exorcist for several decades.

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  • hssuzanne

    I have to comment, simply because a couple months ago I experienced the strongest, most intense temptation, bordering upon obsession, to start smoking again (I quit last year for the last time). It began out of the blue, no triggers or stressors that usually starts this kind of thought…It was horrible. For almost three weeks, I thought all day, every day about smoking and cigarettes. I became resentful inside, and I knew if I wasn’t currently breastfeeding my 8 month old I would have succumbed. I prayed a LOT, especially to our Blessed Mother and my guardian angel for help with this temptation.It finally stopped after almost a month, where I somehow withstood it and didn’t succumb.
    A week later I found out I was pregnant with our sixth baby!
    After reflecting on this, I truly can understand and appreciate the Scripture Matthew 12:43-45-
    “When an impure spirit comes out of a person, it goes through arid places seeking rest and does not find it. Then it says, ‘I will return to the house I left.’ When it arrives, it finds the house unoccupied, swept clean and put in order. Then it goes and takes with it seven other spirits more wicked than itself, and they go in and live there.”
    It was an incessant, prolonged, hard temptation, thoughts were like a swarm of flies buzzing around my head that would only get “swatted away” temporarily with prayer.
    Praise be to God I made it through.

    • LizEst

      Sounds like a real trial. I am glad you understand one must put something good (i.e. the Lord) in place of that temptation. Would that more people understood this. Congratulations on your newborn…and the sixth one on the way! Wow! God bless you, hssuzanne. I loved your avatar!

      ps. For future reference, if you type directly into the combox (communications box), instead of cutting and pasting (if this is what you did), there won’t be so many spaces in your text. In any case, you can always hit the “edit” button underneath your text and go in and eliminate the spacing.

      • hssuzanne

        I commented using my iPhone.. That is strange, the spacing. I ll edit.
        Thank you so much for your well wishes!

        • LizEst

          Thanks for letting us know how you commented. Before this, I only thought it happened via the cut and paste method. So, this was an education. Thank you.

    • Becky Ward

      Great Insight!!

    • JKA

      Bravo! Those types of trials can be so difficult!

    • Marg

      thanks Suzanne for sharing how God brought you through your temptation. This is inspiring for others who may be fighting the same! God bless you!

  • I always thought of it this way – if mental afflictions were only physical, Jesus would have cured them rather than casting out demons. I’m not saying that that there isn’t a physical component as well, but I think we shouldn’t ignore the possibility of a spiritual component.

    Deo Juvante, Jen

  • Laurie

    Food for thought and discussion on the natural versus demonic cause….I have always struggled with this question….what causes the affliction (which is an evil) in the purely natural sense? Is it the ‘fall?…our fallen nature being the root of all sickness and ultimately death? My unresolved question…..” Is the demonic at least always the indirect cause of every affliction?”

    • LizEst

      Good questions, Laurie.

      Sin entered the world because of the fall. And suffering and death are the consequences of that original sin. We are weak because of that original sin, so that, as St. Paul indicated, the good we want to do, we cannot do, and the bad we don’t want to do, we do (cf Romans 8:19). So, we sin because we have been weakened by original sin. We fall to temptation because original sin has left us damaged. Temptation can come from the world, the flesh or the devil. The demonic is not “at least always the indirect cause of every affliction.”

      Sometimes, when we are sick, it IS due to our own sin. For example, if we have abused our bodies, through alcohol, drugs, etc., we might later develop lung cancer or cirrhosis of the liver or something like that. Where did that come from? It came from our abuse of our body, which is a temple of the Holy Spirit. In this case, our suffering is brought on by our own sin…and our suffering, in this case, is expiation for our sin i.e. it is payment for that sin not unlike what happens when someone who commits a crime has to pay a debt to society.

      Sometimes, however, we can get lung cancer without having smoked a day in our lives or been exposed to smoking. Where did that come from? Somewhere along the line, this suffering was the result of someone’s sin and the consequences of that sin…and not ours. It’s kind of like when a someone bombs a sporting event. Those that are injured and killed were not at fault. But, the people who caused the bombing were those that sinned. Who suffers for that sin? Those that were hurt and died. What then? Here, when we join our sufferings to that of Christ, whose passion, death and resurrection have infinite value, our sufferings also have value. And this expiation, joined to Christ, can be applied to those in need of this “prayer of suffering” such as the holy souls in purgatory or even someone still alive on earth.

  • James Patton

    I guess God does not want to interfere with the free will of demons, since He allows mental illness?

    • LizEst

      James–By the way, Happy Feast of St. James today!–Most mental illness is not caused by demons. But, demons can provoke a mental illness if God permits it. If God doesn’t permit it, the demons can’t cause that happen. Remember the famous story of Job in the Old Testament.

      It seems the bigger question you pose is – why would God permit them to do so? We know that God’s ways are not our ways and are, in fact, much greater than our ways. He permits things to happen in order to bring a greater good out of them. To be sure, it is a severe cross to have a mental illness, not only for the person who has it but for their family and friends as well. Oftentimes, when a family member is afflicted with such a severe cross, we see that the family becomes more compassionate toward those who suffer in this manner. Sometimes, we see people who would not otherwise help with something like this, get involved in setting up foundations, homes, and/or services for the mentally ill. So, while we might sometimes think God is “giving away the store” by permitting thus and such to happen, we have to trust that He knows what He is doing. This doesn’t mean we don’t have a responsibility in the face of evil. We are called to do our best to resist the devil. It’s not something we do on our own. As St. Paul indicated, it is in our weakness that we are strong. Why? Because in our weakness, we put our trust in God…which is where it is supposed to be in the first place!

      God bless you, James. Keep your eyes fixed on the Lord.

  • byonan

    I agree that demons can cause mental disorders or illnesses, yet I question part of Fr. Fortea’s description where he says, “Given the internal mechanism that is used to cause temptation – that is, the infusion of a thought or image in our intellect, memory, or imagination…” That is, while I agree that demons stir up our imaginations, etc., I question whether they are capable of “the infusion of a thought.” I suspect the term “infusion” is an inappropriate and inaccurate word to use, and thus may lead to an incorrect understanding of the nature of the influences that demons exert on human beings.

    Does anyone have an authoritative source that could enlighten me on this issue?

    • LizEst

      Fr. Fortea IS an authoritative source. He is a world-renowned expert, has been an exorcist for many, many years, knows more about exorcism than most lay people, clerics and religious, and has written several books on this and related subjects. I have no doubt he means exactly what he says (by the way the Spanish word for infusion is infusión so it’s not a matter of misunderstanding of the term). Fr. Fortea spoke at our parish center recently and his English is excellent. When he spoke, he listened to the translator and corrected her if she got the translation incorrect or if she misunderstood the fine points of what he was saying.

      • byonan

        Thanks for your response LizEst. Yes, Fr. Fortea is an authoritative and reliable source regarding exorcism, but my question is more philosophically and theologically specific regarding what power demons have over the intellect to be simply answered in such a manner. That is, you have appealed to Fr. Fortea’s authority as proof of his statement regarding “infusion of ideas”. However, proof from authority is the weakest form of proof. Hence, my question remains.

        We know that demons can “stir up” our evil thoughts as stated “Not all our evil thoughts are stirred up by the devil, but sometimes they arise from the movement of our free choice” (De Eccl. Dogmat.). (Quoted by St. Thomas Aquinas, S.T. I, q. 114, art. 3)

        The stirring up of evil thoughts is different than the infusion of evil thoughts. Now, when one considers the actual genesis of our thoughts or concepts, it would appear that to say a demon can infuse an idea is to attribute to demons miraculous powers, but we know demons, as powerful as they may be, cannot work miracles in the proper sense of the term.

        On the other hand, if the infusion of ideas does not require miraculous power, then I as far as I can determine at this point, it nonetheless attributes powers to demons not permitted by God. For example, demons cannot move the will, nor can they know our secret thoughts (unless they are revealed in some manner by our actions.)

        In sum, I remain undecided and still search for an answer to my original question.

        • LizEst

          You are right. Demons cannot move the will nor can they know our secret thoughts. But, even we humans can “put a thought into someone’s head” or “infuse a thought” by suggestion or manipulation. That is, we don’t move someone’s will but, by many different methods, we can get someone to think something.

          That is how classical seduction works: someone appeals to whatever they know will get you to think you should give in to them. The more they do this, the easier it gets for them and the more difficult it makes it for you because, although they cannot control your will, they can influence you to engage with your will in a way that will be favorable to the outcome they desire. This does not mean that someone has to correspond to that thought, or sin because of that thought. Evil thoughts are just thoughts, even though they are manifestly evil. It is when we entertain them that we sin. And, if we are particularly susceptible to certain thoughts, the possibility of sinning because of them looms great without the grace of God.

          It’s similar to singing a particularly “catchy” song. If I play that for you, or sing it to you, depending on how much stock you have in it, I can put that song in your head all day, much to your annoyance…or, maybe to your great joy if it is a song in praise of the Lord. What you do with the “tape” or “recording” of that song in your head is where you have responsibility for it. Because demons study us, they have great knowledge of our weak spots. So, when they “infuse” or “put” an evil thought in our heads, they do so knowing the probability of success. We don’t have to give them that satisfaction. We have free will.

          This infusion of thoughts into someone’s head can, quite literally, drive someone crazy. Hence, the ability of demons to cause mental illness. Although demons are not the cause of most mental illness, they are certainly responsible for some of it.

          • byonan

            This is contingent on the meaning one attaches to the word “infuse”. If by “infuse” we merely mean “to imbue or inspire”, then we can say that one person can infuse a thought in another’s intellect. However, if we use “infuse” according to its primary meaning, which carries a much stronger causal connotation (to introduce as if by pouring; cause to penetrate), then neither we nor demons can infuse a thought in another person’s intellect.

            Thus far it appears that Fr. Fortea has either (a) chosen a word that is ambiguous, i.e., easily capable of varied interpretations, or (b) incorrectly interprets demonic influence on the mind is this area.

            At the very least, “infuse” is not the right word to use due to its ambiguity where greater precision is required. Therefore I cannot defend its use in this context.

          • English is not Fr. Fortea’s first language so this could also be a translation issue.

          • byonan

            That’s exactly right, Dan! Something is lost in every translation.

            However, I suppose only Fr. Fortea himself, or someone intimately familiar with his thinking, can give us a final answer on this.

  • jrbarrytx

    There is a marvelous book “The Catholic’s Guide to Depression” by Aaron Kheriaty, MD with Fr. John Cihak, STD. I would suggest anyone struggling with this or has a family member with it, may want to purchase it. I have recommended it to my spiritual adviser. Pope John Paul II says :Depression is always a spiritual trial”. The only reason I suggest this, is it is another way to look a one form of mental illness from a clinical perspective and a Catholic psychiatrist, who weaves not only the medical aspects of this but also brings in the spiritual aspect as well. I have read Fr. Fortea’s book and it is very good but I think we also need to understand this from the clinical perspective as well.

    • LizEst

      Thanks for sharing that resource. No doubt it will help many. I like the fact that the priest who helped with it has a Doctorate in Sacred Theology. (The Avila Institute: , which will begin classes this fall, will offer certificates in spiritual theology at different levels, one of which will be at the graduate level.)

      It’s important to note that Fr. Fortea did not say that demons cause all or even most mental illness. He said they CAN cause mental illness. But, readers here should not take that to mean that they are the primary cause of mental illness.

  • Pauline63

    I discovered that my husband of more than 25 yrs. has been having a very LONG TIME “affair”. therapists say he is a sex addict Is this an excuse? Have demons/devil caused this “mental illness”? Did God allow it?

    • LizEst

      My sympathies, Pauline. This kind of betrayal is a very tough cross to bear.

      Addictive behavior is a disease but not an excuse. The reason addiction is so difficult to stop is because it acts like an opiate on parts of the brain. And, where the body has a weakness in combating this effect, the addiction sets in. Addictive behavior feeds the addiction and “cements” the destructive behavior patterns even more. People who are addicts will behave destructively no matter what else goes on around them, unless, of course, they are able to amend their behavior patterns. With a little education, addicts know their actions are destructive but have very little will power to quit. Various 12 step programs have great success because the people in these groups acknowledge they are powerless against the behavior. By acknowledging their weakness and relying on “a higher power” (God), they have had much success in stopping the behavior.

      Do demons cause this addictive behavior every time? I would say no. Classically, our human weakness is susceptible to three things: the world, the flesh and the devil. Any or all three can be a temptation. Can demons cause sex addiction? I would imagine so. Do they always? Probably not. We do have free will, after all. We don’t have to give in to temptation.

      Did God allow it? Well, God didn’t stop it. So, yes, he permitted it. God never violates our free will. But, that does NOT mean that He wanted it to take place. God is all good and incapable of evil. The only reason He permits something is to bring greater good out of it in some way. We don’t always know or understand the reasons why. We do our best to fight against these destructive behaviors…and to place our trust in God.

      God bless you, Pauline. This is a very, very difficult thing to go through. My prayers for both of you.

    • Ed B.

      I would doubt that they are the cause, although I am sure they encouraged whatever led to that delightedly. Having been an addict, I can say that being any kind of addict is not an excuse to do anything, it just means you will have to work harder to resist doing that thing–you have an obsession about something, and/or physical symptoms if you don’t get what you’re obsessed about. Sex addiction doesn’t cause physical withdrawal (yeah there is dopamine, oxytocin and other things, but that is nothing compared to the DTs and it is over repeated activity lessened), so I would get him to a therapist who isn’t an idiot and believes in free will, or at least one who has the appreciation that belief in free will changes outcomes better than no belief in it, and therefore acts accordingly

      • LizEst

        Thanks for weighing in Ed B. God bless you.

      • Pauline63

        Thanks for your insight, Ed B. Fortunately, we have both found excellent, caring, Christian therapists and are working toward healing, whether together or separately. God Bless you!

  • Thank you, Fr. Fortea for this illuminating Post. The clarification below is timely and must be borne in mind before one concludes all Mental Illness are manifestation of Demonic Possession:

    ” In most cases, mental illnesses have purely natural causes.”

    It is regrettable that in the Charismatic, Pentecostals and Evangelical brand of Christianity, all Mental illnesses are branded of Demonic Possession and/or Obsession. And the tragedy is that with this belief many sufferers who would get relief by going to the Doctors are, instead subjected to repeated indignities of undergoing numerous public “Deliverance/Exorcism” Sessions done with no regard for the modesty or respect of the dignity which should be accorded to the sufferers themselves and their loved ones.

    • LizEst

      Yes, most mental illnesses have natural causes. We should heed this information from Fr. Fortea, an expert exorcist. Thanks Mary.

      • Thank you, Liz. I underwent a most painful experience one day when a Member of our Eucharistic Apostolate of the Divine Mercy vehemently declared that ALL Mental Illnesses are a manifestation of Demonic Possession and Obsession. No amount rational suggestions from my colleagues, that the mind, like all other organs in the human body can and does get sick. And the mind, too, being a human organ, can and does get be afflicted by normal, medically verifiable, explainable and curable illnesses well documented over the years. The pain I underwent lingers to this day.

  • Dear Adsphe – isn’t it a bummer when you want to tear someone down and you run into our wonderful combox moderation tool? My sincerest prayers for blessings on you.

  • dustin

    My name is Dustin, Im 35 and I seem to suffer from depression. My mother suffered from depression as well, right up until her suicide in 1985. I also suffer(d) from addiction. I tried to commit suicide – a couple of times. I dont want to commit suicide anymore but I still am depressed. I constantly feel “lazy”, I dont work, and I dont really have friends. I have met with counsellors and psychiatrists but here I am still alone.. I need someones help! I dont want to be this person that I have become anymore! I will go where ever I have to go but I need someone’s help please..
    If there is anyone out there that can help me so that I can have a life again, I will be forever grateful. I dont use any illicit drugs anymore, nor do I drink. I also dont have much money but I could sell my motorcycle to get some cash and Im also on disability which provides me with a small income.
    If there is anyone out there that think they can help me, please dont hesitate in contacting me…

    • Tessye

      Dear Dustin, God bless you. I will include you in my prayers for God to show you a solution (medical/emotional/spiritual). Just as many of us may suffer with similar problems, they differ within and we may not understand the why’s and what’s behind them; only He knows and understands all without explainations. You must keep searching and seeking a solution and most of all, trust in Him (Matthew 7: 7-8 and Matthew 11:29-30).

      • dustin

        Thank you Tessye, I appreciate your kind message 🙂

    • Jeffrey Pascu

      Hi Dustin,
      I can resonate with your experience. One time I became also depressed due to many problems but a thought came to me a powerful word that saves me….. You know what it is?…. It’s “Jesus”… “I prayed. I love you Jesus pls. save me” many times this thought leaves me..

      Afterward, Pray to the Blessed Virgin Mary.. Hail Mary.. This is difficult but keep on fighting..

      Your in my prayer dustin.. God Bless you and your family!



    • Sruan

      Hi Dustin, I will keep you in my prayers and please urge you to get help. I suggest contacting some local churches and ask them if they have a Stephen Ministry program. You arenot alone and you are a loved and valued member of the family of Christ. My best friend died due to her struggle with depression and it is never the answer. The dark side wants you to feel isolated but make even small strides and goals by going to church and becoming more involved or visits to a library. Remember Romans 8:38. Peace and prayers to you! Sue

      • dustin

        Hi Sue,
        Thank you for your message and prayers. What is a Stephen Ministry program?

  • Sruan

    Hi Dustin, u will get through this, just turn to Jesus on a daily basis. read the bible even on 10-15 minute basis everyday or Monday thru Friday — u don’t need to be perfect, Jesus makes us perfect. Believe me I know. Not knowing where u live, most churches (bigger ones) will have a Stephen ministry program. It is basically a way for people to help each other in the Christian forum and not have the minster or priest get involved (because of their heavy workloads).

    I can tell that u are a wonderful person and don’t give into negative, dark temptations. Jesus needs u here to be a warrior on Earth until HE calls u home! Live for your mom, just as I do for my best friend, Carrie.

    Call a Minnesota based church such as Advent Lutheran or St Joseph the Worker Catholic Church for a referral to a Stephens Ministry program. they are actually worldwide now.

    Don’t forget daily wholesome steps, small steps towards to Jesus. 🙂

  • Sruan

    Lastly and importantly, u need to get help medically. Brain chemistry is at work. It sounds like u have a family history of depression. U need to be kind and loving toward yourself. You are not lazy but dealing with a difficult illness in the same way of someone dealing with diabetes or cancer. Seek Jesus and He will help.

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