Though demons can enter and possess any unbeliever, they cannot enter into the body of those who belong to the Lord. There are a number of reasons why this is so.
Greater Is He
The Bible says that the one who indwells believers is greater than the one who is in the world.
You are of God, my little children, and have overcome them: because greater is He that is in you than he that is in the world (1 John 4:4).
Delivered
Those who have trusted Christ have been delivered from the possibility of demonic possession. Paul wrote.
in which you once lived, following the course of this world, following the ruler of the power of the air, the spirit that is now at work among those who are disobedient (Ephesians 2:2).
The believers do not live any more under their authority.
He has rescued us from the power of darkness and transferred us into the kingdom of His beloved Son, in whom we have redemption, the forgiveness of sins (Colossians 1:13,14).
Nothing In Common
Believers have nothing in common with darkness or Satan. The Holy Spirit, and a demonic spirit, cannot co-exist in the same person.
And what agreement has Christ with Belial? or what part has a believer with an unbeliever? (2 Corinthians 6:15).
No Biblical Example
Finally, there is no example in Scripture of a believer in Jesus Christ being demon-possessed. All cases of demonic possession were with those who were unbelievers.
Passages In Support?
Sometimes the following passages are cited as support of believers being possessed. Paul ordered the church of Corinth to deliver a believer over to Satan.
to deliver such a one unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus (1 Corinthians 5:5).
There is no evidence that the person whom Paul delivered over to Satan became demon-possessed.
Two Others
The Bible speaks of two other individuals who were also delivered over to Satan.
of whom is Hymenaeus and Alexander; whom I delivered unto Satan, that they might be taught not to blaspheme (1 Timothy 1:20).
As is the case with the believer in Corinth, there is no indication that either of these men were ever demon-possessed.
People Taken Captive
Another passage speaks of people being taken captive by the Devil.
and they may recover themselves out of the snare of the Devil, having been taken captive by him unto his will (2 Timothy 2:26).
The people under discussion in this context are not believers. Consequently there is no Scriptural support for the idea that Christians can become demon-possessed.
What About Stories Of Believers And Demons?
If this is the case, then what about the stories that circulate with respect to believers and demon-possession. Examples are provided of believers who exhibit symptoms of demon possession. When people give examples of believers being possessed, there are a number of questions that immediately arise, "Were these victims of demon possession really believers?" "Were they actually possessed with a demon, or is there another possible explanation for their behavior?" Since the Bible gives no support that a believer can be possessed by a demon, some other explanation must be in order.
Permanent Indwelling Of Holy Spirit
The issue is clear. It is not whether a
professing Christian can be demon-possessed, but rather can a genuine, "born again" Christian become demon-possessed? The Bible teaches that those who have trusted Christ are permanently indwelt by the Holy Spirit.
In Him you also, when you had heard the word of truth, the gospel of your salvation, and had believed in Him, were marked with the seal of the promised Holy Spirit; this is the pledge of our inheritance toward redemption as God's own people, to the praise of His glory (Ephesians 1:13,14).
New Creation
Believers are a new creation in Christ.
So if anyone is in Christ, there is a new creation: everything old has passed away; see, everything has become new! (2 Corinthians 5:17).
Body Temple Of Holy Spirit
The body of the believer is now a temple of the Holy Spirit.
Or do you not know that your body is a temple of the Holy Spirit which is in you, which you have from God? and you are not your own (1 Corinthians 6:19).
Cannot Separate The Believer From The Lord
The Bible says that such evil powers cannot separate the believer from the love of God.
For I am persuaded, that neither death, nor life, nor angels, nor principalities, nor things present, nor things to come, nor powers, nor height, nor depth, nor any other creature, shall be able to separate us from the love of God, which is in Christ Jesus our Lord (Romans 8:38,39).
Specially mentioned are the angels and principalities - angelic orders. Not even they can separate the believer from the love of God. All of these things would make demon-possession an impossibility for the believer.
Spiritual Balance Needed
Satan and demons are defeated foes, yet they are still very active in this world, causing much harm. Though they cannot possess and control a believer, they can cause a number of problems.
Summary
The Scripture does not teach that a Christian can be possessed by a demon. The believer is "in Christ,"- one of His. Every example in the Bible of a person being demon-possessed concerns an unbeliever - there are no examples of believers being possessed. Furthermore, we must be careful not to rely on stories of believers and demon-possession - many other explanations are possible. The Christian, who is indwelt by the Holy Spirit, need not fear demon possession. Yet, demons do attack believers in various ways. Therefore, it would be wrong to say that they cannot have any affect on the Christian.