I was talking with someone tonight about this subject. I hold to the belief that since we are sealed to the day of redemption that we can not be “possessed” by a demon and have the Holy Spirit dwelling in our mortal flesh. Ephesians 4:30 says:
30And do not grieve the Holy Spirit of God, with whom you were sealed for the day of redemption.
And here:
2 Corinthians 1:21-23
21Now it is God who makes both us and you stand firm in Christ. He anointed us, 22set his seal of ownership on us, and put his Spirit in our hearts as a deposit, guaranteeing what is to come.
And Ephesians 1:13: And you also were included in Christ when you heard the word of truth, the gospel of your salvation. Having believed, you were marked in him with a seal, the promised Holy Spirit,
I know that a believer can go through great sickness, suffer depression, and a whole host of things but I believe that if you are in Christ you may be oppressed but not possessed.
I am super tired so I just cut and paste this article from www.GotQuestions.org . I really love their site!
Question: “Can a Christian be demon possessed?”
Answer: The Bible does not explicitly state whether a Christian can be possessed by a demon. However, since a Christian is indwelt by the Holy Spirit (Romans 8:9-11; 1 Corinthians 3:16; 6:19), it would seem unlikely that the Holy Spirit would allow a demon to possess the same person He is indwelling. This is sometimes a controversial issue; however, we strongly hold to the belief that a Christian cannot be possessed by a demon. We believe there is a distinct difference between being possessed by a demon and being oppressed or influenced by a demon. Demon possession involves a demon having direct control over the thoughts and/or actions of a person (Luke 4:33-35; 8:27-33; Matthew 17:14-18). Demon oppression or influence involves a demon or demons attacking a person spiritually and/or encouraging him/her into sinful behavior (1 Peter 5:8-9; James 4:7). Notice that in all the New Testament passages dealing with spiritual warfare, we are never told to cast a demon out of a believer (Ephesians 6:10-18). Believers are told to resist the devil (1 Peter 5:8-9; James 4:7), not to cast him out.
It is unthinkable that God would allow one of His children, whom He purchased with the blood of Christ (1 Peter 1:18-19) and made into a new creation (2 Corinthians 5:17), to be possessed and controlled by a demon. Yes, as believers, we wage war with Satan and his demons, but not from within ourselves. The apostle John declares, “You, dear children, are from God and have overcome them, because the One who is in you is greater than the one who is in the world” (1 John 4:4). Who is the One in us? The Holy Spirit. Who is the one in the world? Satan and his demons. Therefore, the believer has overcome the world of demons, and the case for demon possession of a believer cannot be made scripturally.
Recommended Resource: Angels: Elect & Evil by C. Fred Dickason.