Jesus gives the answer in Matthew 12:25 "And Jesus knew their thoughts, and said unto them, Every kingdom divided against itself is brought to desolation; and every city or house divided against itself shall not stand. And if I by Beelzebub cast out devils, by whom do your children cast them out? there fore they shall be your judges. But if I cast out devils by the Spirit of God, then the Kingdom of God is come unto you. Or else how can one enter into a strong man's house, and spoil his goods, except he first bind the strong man and then he will spoil his house."
We see that Jesus is saying if someone wants to rob someone they must first bind the owner of the house to steal from them. The Holy Spirit is the Strong Man, the owner and if the devil is going to possess someone He must first deal with the Holy Spirit. So the answer is "no, Christians cannot be possessed!" God is almighty and the devil could never bind Him.
We see that Jesus is saying if someone wants to rob someone they must first bind the owner of the house to steal from them. The Holy Spirit is the Strong Man, the owner and if the devil is going to possess someone He must first deal with the Holy Spirit. So the answer is "no, Christians cannot be possessed!" God is almighty and the devil could never bind Him.