There is no record in the New Testament wherein we can find any true believer being possessed by evil spirits. There was no exorcism ministries practiced among believers toward fellow believers.
The Holy Spirit is greater than Satan:
1Jo 4:4 You are of God, little children, and have overcome them, because He who is in you is greater than he who is in the world.
Satan cannot even touch one of God's children to injure or harm him (and demonic possessions are always harmful and injurious):
1Jo 5:18 "...he who has been born of God keeps himself, and the wicked one does not touch him."
The Lord Jesus Christ is the Good Shepherd who laid down His life for saved sinners. He who laid down His life will protect His sheep with all His might from demonic possession:
Joh 10:28 "And I give them eternal life, and they shall never perish; neither shall anyone snatch them out of My hand.
The believer (the entirety of him including his physical body) is Christ's possession. Look, it is in Christ's hand. The Good Shepherd assures that no one shall be able to snatch the saved sinner away from His hold to possess him
When the Lord Jesus rebuked Peter and called him "Satan" in Matthew 16:23, he was not indicating that Peter was possessed by Satan. No, He used the word "Satan" to mean adversary. Peter was being adversarial to God's cause.
Mt 16:23 But He turned and said to Peter, "Get behind Me, Satan! You are an offense to Me, for you are not mindful of the things of God, but the things of men."
In another translation, the word "adversary" is used:
Mt 16:23 and he having turned, said to Peter, `Get thee behind me, adversary! thou art a stumbling-block to me, for thou dost not mind the things of God, but the things of men.' (YLT translation)
Evil spirits only dwell in a house (man's body) wherein God the Spirit does not dwell and occupy:
Mt 12:43 "When an unclean spirit goes out of a man, he goes through dry places, seeking rest, and finds none.
44 "Then he says, 'I will return to my house from which I came.' And when he comes, he finds it empty, swept, and put in order.
45 "Then he goes and takes with him seven other spirits more wicked than himself, and they enter and dwell there; and the last state of that man is worse than the first. So shall it also be with this wicked generation."
