While I do not believe a Christian can be demon possessed at all(unless fully backslidden), I do believe Christians can be oppressed of the devil. Otherwise, good topic.
It is absolutely true that every Sunday morning the wheat and the tares go to church. The tares are unable to see they are tares and simply assume they are wheat and all is well. The tares have limited protection from God but the wheat who trust under His wing can have tremendous protection and full sanctuary.
The problem arrives when we sin. Demon possession is a sin leated issue. If we as Christians sin and repent we can once again have God's protection. If we sin and do not recognize it is as sin, God's hand of protection may lift, to one degree or another and this is where a Christian gets into trouble.
Case in point, we have a man who has recently posted that we should only love those of our color. He is advocating some bizarre racist teaching that is not found in the bible. His teaching is against the biblical concept that we stand before God equally. His thoughts have created a stronghold (false/sinful pattern of thinking) and he is unrepentant.
I have no idea if he is possessed but he certainly can be. If he is the demon will attempt to reinforce his error and he may become very rigid in his thoughts on that manner. This is a good example of how a Christian can become possessed.
Now suppose he see's he error and repents and begs God for forgiveness. God is just to forgive him but he still has will have the problem of the demon still residing in him unless God removes it Himself. Demons will not leave voluntarily. They must be cast out (forced out), one way or the other.
So I can agree that a Christian in God's will and doing things as God wants and keeps his/her sin doors closed and when sin occurs ask ing for repentance--This person is not likely to have demon. So I agree with you in principle.
