In charismatic and Pentecostal circles the question is: 'Can a believer who is baptized in the Spirit have a demon? Absolutely not!' is the standard answer. 'The Holy Spirit cannot dwell in the same body as a demon!' This is often spoken with the insistence of a slogan, to close the mind to further inquiry.
However, this answer cannot be supported by scripture. In fact, it is an extra-scriptural piece of logic that rests on an assumption. It is dangerous to assume that Satan and his demons have some kind of hands-off policy when it comes to believers while the truth is that believers are the very objects of their wrath and attack.
In the New Testament, the Greek word 'daimonizomai' is used to express the presence of demonic spirits within a person. What this word means is: 'to be demonized; to be under the power or influence of a demon in certain areas; to have a demon.'
In the King James Version of the Bible this particular Greek word is translated 11 times as 'to be possessed with devils'. The word 'possessed,' however, is a misleading translation for this Greek word. To English speaking people the term 'possessed' implies total ownership of something. This concept, as pertaining to the relationship between a demonic entity and a person, has no support in the scripture or in the original intent of the Greek word. There is no suggestion in the scripture that a demon has totally taken over a person as the word 'possessed' implies. Even the Gaderene demoniac had enough humanity to cry out to Jesus for help.
Rather, after close scriptural study, it can be seen that the effect of demons upon people was usually in one or more areas of the personality - not the whole person. The best translation of this Greek word is: 'to be demonized' or to 'have a demon.'
A useful analogy would be the city of Chicago. In the 1930's Chicago had a mayor over the town, but the Mafia definitely ran parts of the town. Even so, while a believer may profess Jesus Christ as Lord of their life, it's quite possible that certain areas of the life may be under the domination and controlling influence of demonic spirits, i.e. an area of jealousy, lust, or annoying and compulsive habits.
Because of a scriptural misunderstanding of exactly what occurred at their spiritual rebirth, many believe that they are somehow immune, or instantly free, from the strongholds, bondages and curses accumulated during a lifetime of sin.
A careful study of the New Testament will reveal that our spiritual rebirth was just that, a 'spiritual' rebirth. Jesus said in the third chapter of John; 'That which is born of the Spirit is spirit.' It was the human spirit that received life when we confessed our sins and were born again. God told Adam that in the day he ate of the forbidden fruit he would die. Yet he went on to live for many hundreds of years. What died in Adam when he fell into sin? Obviously it was that same part of his nature that Christ came to bring back to life - his spirit.
The Apostle Paul tells us in 1 Thessalonians 5:23 that man is a tripartite being: spirit, soul and body. For this threefold being (created in the image of his threefold Creator) God has provided a threefold salvation. When one is born again, the spirit is infused with the very life and presence of God. This burst of inner life (called justification) often serves to liberate the person from bondages in the soul and, sometimes, even sicknesses in the body. However, regeneration in the spirit does not mean complete salvation and perfection for the soul. This is evident in any believer's experience.
The second-fold of God's salvation involves the daily process of cleansing, changing, conforming and renewing the soul into the likeness of the Lord. The soul (composed of a man's mind, will and emotions) is far from perfect. It is in this realm where the habits, patterns and bondages of the past may still be found. By careful and consistent conformity to the will of God, directed from the presence of God in the human spirit, the soul is slowly transformed to become a pleasing habitation of the Lord. This process is called sanctification (or 'set apart' unto holiness).
Finally, the third part of God's salvation involves the body. When Christ comes again, the scriptures tell us that we shall be changed and shall receive new bodies like unto the Lord's new body after his resurrection. This is called glorification. It is also evident, from the teachings in the New Testament, that the degree of glory expressed through our bodies then will be related to the degree of glory allowed to manifest through our souls now.
In justification (our past salvation) we were delivered from the penalty of sin (eternal separation from God). In sanctification (our present salvation) we are being delivered from the power of sin in our lives each day. In glorification (our future salvation) we shall be delivered from the very presence of sin.
The scriptures are full of pictures, analogies and parables depicting the teaching of man's tripartite being with God's provisions of salvation. When Jesus cleansed His Father's temple, full of wrath against the men that had turned a house of prayer into a den of thieves, He was revealing God's heart. We too, are the temple of God and thus need the invading presence of the holy Lord to cleanse us from the 'thieves and robbers' within.