I have a question. How should we respond to someone who tells us they think they are possessed by demons?
To a certain extent it is situational. Generally speaking it is probably not a good idea to knowingly engage the demon. First, they are very clever and have a long history of misleading, and manipulating people in ways both subtle and gross. When they are not trying to deceive you outright they try to provoke you into behaving in an unchristian manner…either in anger or in pride and vainglory. Second, most of us are not particularly holy…not as we should be, though you may be certain demons both fear and hate Christians of any degree of spiritual life/depth. It is holiness, especially humility and love in Christ that burns them. Third, as noted most who had such troubles are not "possessed" in any definitive sense, and how much the demon is in control or expressive can be a matter of several degrees, from all but overwhelmed, to sad and creepy, to a little off on this or that thing…it is the person who struggles who needs our kindness and our prayers. For those, troubled but not too far gone…building a loving relationship over time, inviting them to church, helping make contact with a priest, just being a friend present in person and in prayer can make a great deal of difference. Some, with such help find the strength to push back and reclaim their lives from their tormentor.
I have read…somewhere recently, I forget where, that back in the third or fourth century, one Christian leader went so far as to claim that any Christian who could not cast out a devil was not a true Christian. Of course, what most of us are today is nothing like the saints of that era.
St. Issac the Syrian said that the Christian's heart should burn with love for all creation, including the demons. I have wondered since reading that what avenue of love is even possible to show to them…certainly unless one is deeply holy and graced any sort of engagement other that an exorcism is likely to have unwholesome consequences. As I pondered the idea it seemed to me the only way to show them love was to ignore them. And this is true not just with those troubled with devils but when we find ourselves tempted as well. If we are tempted by them and we sin…both of us have sinned…us and the one who tempted us….So if we ignore them out of love so that we do not add to their sin by yielding to their temptations, we've done just about all we can do for them. In this light, even exorcism expresses a sort of love…in that expelling them limit's their sin with respect to the person they had invaded. We note even in the NT Christ dealt sternly with them, but not in an overly emotional belligerence. He knew who they were and from when they had fallen. Anyway, this is how it seems to me, and it is possible I may be mistaken on some point or another. Check with a priest.
If one is with a somewhat demonized person, one need not engage the person in deep theological conversations. For laymen who are not well exercised in holiness, the best thing may be to silently pray the Jesus prayer for yourself and for the other person, "Lord Jesus Christ, have mercy upon Thy servant."
As a parting thought on the subject I am reminded of an old story…which I do not know if it is true or not or where I first encounter it, though it seems to be set in the time of the desert fathers…or if not then in some similar situation to theirs.
There was once an ancient monastic, a simply godly hermit of many years who bothered no one, and attended to his rule of prayer. It came to pass that a devil came to torment him him, to make noise, knock things around, and otherwise do whatever he could to disturb this old monk's prayer. It went on a long time, but a day came when the devil was in the midst of his harassment when the old monk turned and fixed him with the sign of the cross, then went back to his prayers.
The devil found it could not move at all and found himself burned by the prayers of the old monk and so pleaded to be set free promising never to bother him again. After a long while the monk turned again to the devil and said, "One condition will I release you. Sing for me the song which the angel sang at their creation."
The devil laughed, and said that he no longer remembered it, besides it would be the death of mortal flesh to hear that song. The old monk returned to his prayers. Once again the devil became agitated and asked to be released promising to not bother him anymore…the monk continued praying.
"If I sing it you will die," said the devil.
"Well, then you can stay there and listen to my prayers until the Lord takes me," said the old monk.
"No," said the devil, "I will try." And with that he began to sing. At first it's voice was raw and shrill and ugly and it stopped and stammered over the words as it tried to recall them. But as it continued, the memory came again, and the words grew stronger and more sure, and the voice found it's pitch and tenor and it sang the song of the morning when all the sons of God sang together, verse after verse throughout the night. And when the dawn came it revealed the old monk laying dead across the feet of a great and glorious angel still singing the great and holy praises of God.