To be able to answer the question of whether a Christian can be indwelt by a demon or not it will help to clearly understand what the biblical words actually mean in the New Testament in context rather than how they are used today by Christians who define their convictions by what they have experienced, seen or heard.
Daimonizomai
The Greek term daimonizomai is used 13 times in the New Testament and only in the Gospels. The following are the references where this word is used and how it is commonly translated into English:
“those which were possessed with devils” Mt.4:24; “that were possessed with devils” 8:16; “possessed with devils” 8:28; “possessed of the devils” 8:33; “possessed with a devil” 9:32; “one possessed with a devil” 12:22; “vexed with a devil” 15:22; “them that were possessed with devils” Mk.1:32; “him that was possessed with the devil” 5:15; “to him that was possessed with the devil” 5:16; “he that had been possessed with the devil” 5:18; “he that was possessed of the devils” Lk.8:36; “of him that hath a devil” Jn.10:21.
Those who teach that Christians can have demons usually prefer to translate this Greek word as ‘demonized.’ They make much of how this word is translated into English. They are willing to say that Christians cannot be possessed by demons, in the sense of being owned by demons, but they do teach that Christians can be demonized, meaning indwelt or outwardly oppressed by demons. They sometimes teach that full demon-possession is rare and confined to unbelievers but that demonization is frequent and is common amongst all believers. They try to infer that purely on the basis of this confusion in the translation of this word many Christians reject the teaching that they can have demons indwelling them.
They teach that this term daimonizomai can mean someone controlled and indwelt by a demon but also someone who is outwardly oppressed and influenced by a demon. They make it a broad term making it a common and frequent experience amongst Christians in the Church. They also make it a term of degrees meaning that it can range from extreme possession to mild oppression and can be used of those who are unsaved as well as those who are saved.
To Have a Demon
The Greek term echō daimonion is also used in the New Testament in connection to a demon’s influence upon a person. It basically means ‘to have a demon.’ This is used 8 times in Matthew, Mark and John. Once it is used in connection with the Demonic of Gadara (Lk.8:27) who is also called daimonizomai three times (Mk.5:15, 16, 18) and who is said to be a “man with an unclean spirit” (Mk.5:2). This reveals that these three terms are synonymous in describing the state and condition of the one man. The other seven times this word is used it is in connection to the accusation that John the Baptist and Jesus Christ both “had a devil.” The following eight references reveal how and where it is translated into English:
“He hath a devil” Mt.11:18; “He hath a devil” Lk.7:33; “which had devils” Lk.8:27; “Thou hast a devil” Jn.7:20; “hast a devil…I have not a devil… hast a devil.” Jn.8:48-49, 52; “He hath a devil” Jn.10:20
Possess
Nearly all those who promote the teaching of the demonization of Christians try to infer that our English version of the Bible is wrong in speaking of demonization as possession. But it will be clearly seen in the following quotes that the word possession is a very good English translation of daimonizomai and conveys an accurate meaning as long as the English word is understood correctly.
The Oxford English Dictionary defines it: “Of a person or body of persons: To hold, occupy (a place or territory); to reside or be stationed in; to inhabit (with or without ownership).”
The American Heritage Dictionary defines it: “to gain or exert influence or control over; dominate”
W. E. Vine translates the verb this way: “To be possessed of a demon, to act under the control of a demon.”
The Online Etymology Dictionary defines it: “to hold, occupy, reside in (without regard to ownership)…to hold as property”
All of these translations, definitions and explanations of the English term ‘possession’ perfectly describe the New Testament teaching concerning the indwelling of demons. Those who try to infer that daimonizomai cannot mean ‘possession’ are totally incorrect. They are merely redefining words in order to establish their own teaching. The translators of the King James Version of the Bible had a full grasp of the English language as well as Greek and Hebrew. They also had a full grasp of what the New Testament taught in connection with daimonizomai.
Demonization
If we study each reference where these terms are used we are able to then clearly define and summarize the biblical teaching of demon possession or demonization as revealed by the Spirit of God in the written Word.
1. A person who is ‘demonized’ or who ‘has a demon’ is one who has one or more demons dwelling inside of them, in their body. Demons literally make this person their house. This is not an outside influence but an internal influence. These terms are never used in connection with oppression, temptation or other attacks which come from the outside. The tense of daimonizomai means it was something that happened at an actual point in time in the past.
2. When demons indwell an individual they exert an abnormal, unnatural, control and dominating influence upon the person physically or mentally. This may be manifest through dumbness (Mt.9:32), blindness (Mt.12:22-29), insanity (Mt.17:15), as well as in cutting oneself and nakedness (Mk.5:5, 15). It would seem that the demons also have the ability to speak and act freely without restraint from the individual (Mk.5:7-9). The personality of the demons may literally be manifest and so utterly hide the personality of the man or woman they indwell. It is a serious dominating influence not a mild influence or natural fear. Demonization manifests in mental and physical torment rather than any particular dominant sin.
3. The only cure is that the demon or demons be cast out through the power and authority of Jesus Christ. Every time Christ encountered such a person we read of Him casting the demon out. Each time that the demon or demons left a dramatic change was brought about physically, mentally and spiritually that was immediately noticeable to all and experienced by the individual.
4. These terms never refer to a born-again believer. Not once is there any sign in any of the 13 uses of daimonizomai that one single believer was referred to as demonized. Not one. I would encourage you to simply read through these verses listed above in order to confirm this for yourself. Again the 8 times that echō daimonion is used it always refers to a false accusation against Christ and John the Baptist apart from once. The one time it is used differently is when it refers to the Demonic of Gadara. So the only actual example of someone ‘having a demon’ is in extreme demon possession.
Conclusion
When such words and teachings as demonization and of a person having a demon are used in connection with Christians we can see from scripture that it is being taken out of context as well as misused and abused. Demon possession is real. The terrible affliction and torment of those possessed is very real and terrible. But the teaching that most Christians are demonized, either indwelt by a demon or at least controlled by a demon, is totally unbiblical. The contemporary teaching of demonology is a million miles from the biblical teaching of demonology. Demonization does happen today but all unbelievers are not demonized never mind most Christians.