Can a Christian have a demon? Most persons who object to this idea say that since we are Christ's possession, we cannot possibly be “possessed” by a demon. Our answer is that the phrase, “demon possessed” is never found in the Greek New Testament. The Greek actually uses the verbiage, "to have" a demon, “to be in” a demon, or to be “demonized” (Gk.: daimonidzomai). Wherever English translations of the Bible say “demon possessed,” they are mistranslating one of these three terms.
Actually, total possession is very rare even in the Bible. The man with “Legion” is a notable exception. But note that it took a whole legion of demons to possess him. A Roman legion had upwards of 6,000 soldiers. Why so many demons? Because no demon is capable of complete control over every aspect of a person. Rather, each demon specializes in a particular area. For instance, there is the case of the woman who was crippled by a demon for 18 years (Lk. 13:11). The demon afflicted her body, but her mind remained sane. Or there is the slave girl who told fortunes through the power demons (Acts 16:16), but remained in good health physically. These persons were not completely possessed, but were affected in some compartment of the self.
For instance, look at Ephesians 4:26, 27, which says that if the Ephesians allowed the sun to go down on their anger, they would give the devil a foothold. The word, “foothold,” in the Greek, is topos, which means “place.” This is not a transitory affect. It is a semi-permanent place of residence. We even get our word "topography" from topos. If we let the sun go down on our anger, a demon can find a dwelling place on the map (topography) of our lives.
Or look at 2 Timothy 2:26, which says: “The devil . . . has taken [Christians who believed false teachings] captive to do his will.” He did not take them captive in every way — he did not “possess” every aspect of them. They were not physically crippled like the woman in Luke 13. Nor did they tell fortunes like the woman in Acts 16. They were merely believing and acting upon the particular false teachings in question.
Or look at Acts 5:3, which says: “Satan so filled [Ananias'] heart that you have lied to the Holy Spirit.” Ananias was not completely possessed, but was influenced through the particular sin of lying. In each case, consistent sin allowed the demon a sphere of influence. Mere inhabitation does not constitute possession. If you have a parasite in your colon, it will affect you in a detrimental way. But does that mean you are possessed by it? Demons are spiritual parasites, feeding on unrepented sin.
Some object to the idea that a Christian can have a demon because God and a demon cannot inhabit the same space. Such persons have not taken into account God's omnipresence (meaning He is everywhere at once). Ephesians 4:6, 10 says that God is “above all, through all, in all,” and “fills all things.” By their way of thinking, God must not be in the myriad places taken up by demons. But according to verse ten, God is in every place, no matter what evil has infected it (this is not pantheism, the belief that God is all things; rather, God is in all things).
There are numerous examples in Scripture of Christians who were demonized to varying degrees. For instance, unresolved anger can give demons a foothold (Ephesians 4:26,27). In the last days, some Christians will become demonized through heresy (1 Timothy 4:1). Paul urged Timothy to gently instruct apostate Christians, so that “They will come to their senses and escape from the snare of the devil, having been held captive by him to do his will” (2 Timothy 2:26). Paul handed Hymenaeus and Alexander over to Satan so they would be taught not to blaspheme (1 Timothy 1:20). When a man cohabitated with his father's wife, Paul said, I have decided to deliver such a one to Satan for the destruction of his flesh, that his spirit may be saved in the day of the Lord Jesus (1 Corinthianns 5:5). Nonresistance invites demons: “Resist the devil, and he will flee from you” (James 4:7). The inverse is true: don't resist the devil, and he will pursue you. When Ananias and Sapphira donated money, they lied about the amount they had gotten from the sale of their land. To this, Peter replied, “Ananias, why has Satan filled your heart to lie to the Holy Spirit?” (Acts 5:3a). The Greek word for, "filled," pleroo, is the same word used in the phrase, “filled with the Spirit,” in Ephesians 5:18. Thus, those who are filled with the Spirit can be filled by a demon (but not completely possessed), if they grant it access through serious or continual sin.