In the mid 1980s, I witnessed a young boy set free instantly from inexplicable seizures and bizarre behavior through the power of prayer. Treated by medical professionals for months who were at a loss to explain the underlying cause, the church stepped in with prayer to specifically combat the demonic.
In the 1990s, I witnessed a young woman exhibiting dramatic and inexplicable destructive changes in her behavior, instantly set free - again through the power of prayer.
As the culture abdicates truth and descends into paganism, we are experiencing an exponential explosion in demonic activity. The gospel (light) suppresses by nature the forces of darkness. When that light is withdrawn from the public square, darkness becomes inevitable. By definition, darkness is the absence of light.
Unfortunately much of the evangelical community is silent on the subject of the demonic. [While I do not agree with much of their theology, to its credit, the Roman Catholic church formally recognizes the reality of supernatural evil and the rite of exorcism, using specially-trained clergy to carry it out. In the past decade, the number of trained Roman Catholic exorcists in the U.S. has quadrupled, but it is still not enough to keep pace with the exploding demand.]
All mental illness is not the result of demonic attack. But if normal medicine, counseling and therapy do not better the condition, then demonic activity should be considered. But since the secular worldview disavows the supernatural, that worldview is fatally unequipped to combat the demonic. By original sin mankind subjugated himself under the power of him who has the power of death (Hebrews 2:15). And even though free from death, Christians (redeemed by Christ) are still subject to temptation and spiritual attack (Ephesians 6:12).
Thomas Acquinas wrote something that is pertinent: He (Satan) may attack man's body from without (obsession), or assume control of it (the body) from within (possession). As we gather from the Fathers and the theologians, the soul itself can never be "possessed" nor deprived of liberty, though its ordinary control over the members of the body may be hindered by the obsessing spirit (cf. St. Aug., "De sp. et an.", 27; St. Thomas, "In II Sent.", d. VIII, Q. i; Ribet, "La mystique divine", Paris, 1883, pp. 190 sqq.).
Among the ancient pagan nations demonic possession was frequent (Maspero, "Hist. anc. des peuples de l'Orient", 41; Lenormant, "La magie chez les Chaldéens"), as it is still among their successors (Ward, "History of the Hindoos", v., I, 2; Roberts, "Oriental Illustrations of the Scriptures"; Doolittle, "Social Life of the Chinese"). In the early 21st century, the ancient evil is now resurrecting itself to heights of power and activity that was previously suppressed by the spread of the gospel in the West. The ruthlessness, barbarism, sadism and savagery of the Islamic State (ISIS) is a contemporary example of powerful demonic activity.
In the New Testament, demonic activity is not uncommon. The victims were sometimes deprived of sight and speech (Matthew 12:22), sometimes of speech alone (Matthew 9:32; Luke 11:14), sometimes afflicted in ways not clearly specified (Luke 8:2), while, in the greater number of cases, there is no mention of any bodily affliction beyond the possession itself (Matthew 4:24; 8:16; 15:22; Mark 1:32, 34, 39; 3:11; 7:25; Luke 4:41; 6:18; 7:21; 8:2). The effects are described in various passages (Mark 9:17, 21). The possessed are sometimes gifted with superhuman powers (Mark 5:2-4). Some of the unfortunate victims were controlled by several demons (Matthew 12:43, 45; Mark 16:9; Luke 11:24-26); in one case by so many that their name was Legion (Mark 5:9; Luke 8:30). Yet, evil as the possessing spirits were, they could not help testifying to Christ's Divine mission (Matthew 8:29; Mark 1:24, 34; 3:12; 5:7; Luke 4:34, 41; 8:28).
The history of the early Church is filled with accounts of combatting the demonic. A quotation from Tertullian (155 – c. 240 A.D.) as he addresses the pagans of his time: "Let a person be brought before your tribunals who is plainly under demoniacal possession. The wicked spirit, bidden speak by the followers of Christ will as readily make the truthful confession that he is a demon as elsewhere he has falsely asserted that he is a god" (Apolog., tr. Edinburgh, p. 23). The facts associated with possession prove, he says, beyond question the demonic source of the influence — "What clearer proof than a work like that? What more trustworthy than such a proof? The simplicity of truth is thus set forth: its own worth sustains it; no ground remains for the least suspicion. Do you say that it is done by magic or by some trick of the sort? You will not say anything of the sort if you have been allowed the use of your ears and eyes. For what argument can you bring against a thing that is exhibited to the eye in its naked reality?" And the Christians expel by a word: "All the authority and power we have over them is from our naming of the name of Christ and recalling to their memories the woes with which God threatens them at the hands of Christ as Judge and which they expect one day to overtake them. Fearing Christ in God and God in Christ, they become subject to the servants of God and Christ. So at our touch and breathing, overwhelmed by the thought and realization of those judgment fires, they leave at our command the bodies they have entered."
Contemporary accounts from missionary pioneers in pagan countries today affirm the reality of the demonic. While the worldview of secularists may discount it, the truth of Scripture affirms that supernatural evil forces exist and seek to malevolently influence mankind.
Natural disease/causes versus demonic possession are clearly distinguished in the New Testament: (Matthew 8:16; Mark i, 32, 34). A common assertion of the secularists is that lunacy and paralysis were often mistaken for demonic possession. Matthew did not think so (Matt 4:24). There is a clear distinction between ordinary disease and the demonic in Scripture. In the case of ordinary diseases they were cured quietly in the New Testament and without violence. Not so always with the possessed. The evil spirits passed into animals with dire results (Matthew 8:32), or cast their victim on the ground (Luke 4:35) or left the victim with fearsome attending symptoms (Mark 9:25). The Jews themselves in the gospels made distinction between natural-caused infirmity and demonic activity.
When confronting the demonic, Christ addressed the evil spirits, not their victims. He told His disciples how an evil spirit acted when cast out (Matthew 12:44-45; Luke 11:24-26). He explained why they had failed to exorcize (Matthew 17:19). He warned the seventy-two disciples against glorying in the fact that the demons were subject to them (Luke 10:17-20).
If one discards the demonic as merely the superstitious relic of a bygone era, they must then answer this question: If a belief so intimately connected in Christ's own mind with the mission that He came to accomplish was based on a delusion, why did He not correct it? Why rather encourage it?
The answer is obvious. As Paul warns ... we wrestle with supernatural evil (Eph 6:12).
As the light of the gospel penetrated western civilization during the Middle Ages, the darkness of demonic activity receded. Light dispels darkness by nature. However, as the gospel now dims in the West, an ancient and fearsome supernatural enemy is now rearing its dark head, enslaving multitudes in destructive behavior.
Only the Church is empowered to successfully combat this supernatural evil.