Exorcism is spiritual warfare against demons. Demons do not have a body to kill, so the type of warfare waged against them is an area denial attack where you want to cast them out a person, place, or thing, and then keep them and their influence permanently out of that battlefield.
[header](Can a Christians have a demon?)
The Bible teaches that demons can inhabit places (), things (), and non-Christians (), but is silent on whether they can inhabit Christians except for possibly the story of Annanias (). On the other hand, there is no Bible verse that teaches that Christians cannot have a demon, so a theological case has to be built one way or another rather than rely on a clear Scriptural teaching.
The debate turns on whether the Holy Spirit and a demon can co-exist in the same person. The Holy Spirit filled king Saul (), but then left due to rebellion () and a demon tormented him (). King David pleaded for God to not take the Holy Spirit from him (), but losing the Holy Spirit is not possible for a believer () and so that biblical case does not apply to the theory that the Holy Spirit cannot be co-located with a demon. However, there is a story of Old Testament prophets who were at least influenced by an evil spirit to lie while presumably still having the Holy Spirit, but the evidence is not conclusive enough to apply to Christians ().
The other side of the debate appeals to the common experience in non-Western contexts of Christians being demonized. The secular Western worldview attributes such disordered behaviour to mental illness, but fails to explain the root cause of mental illness. The Bible identifies the root cause of all disorder, including mental illness, as sin (), which then gives demons grounds to harass the person, whether they are inside the Christian or not.
Exorcism then is not a matter of justification where being possessed by a demon implies loss of ownership from the Holy Spirit, something that cannot happen (), but of sanctification where the sin grounds for a demon to harass a Christian is to be cleansed through the repentance and forgiveness of sin. Pastorally then, the debate of whether the demon is inside or outside a Christian is beside the point: Any influence demons have on the Christian is to be resisted () and cast out. Even Jesus had to contend with Satan in the wilderness and cast him out of his presence (), an example of an area denial attack where exorcism does not imply that Jesus had a demon, but was attacked by one.
Jesus said, “You will have trouble in this world, but take heart, I have overcome the world” (). A lot of that trouble is from demons, and so Christians are to be salt () and light () in the world to deny Satan the access and freedom to
Further Reading
The best way to see this overview in action is to read one of our healing methods. The Story Method is a cognitive healing method that is compatible with every Christian tradition and denomination. It uses only that which is common to us all: the gospel. The Whiteboard Method is a Spirit-led, visual healing method that is simple, fast, and effective.
If you are interested in reading more of the theology offered on this site, Who Is Involved in Healing theologically reflects on the different roles in the healing process, while Should Healing Be Free explains the different business models for healing, and why we chose to use a free model for this site. How Can I See God explains how sin separates you from being able to experience God, and How Do I Stop Sinning gives the theology of addiction and how to break free of it through the gospel.