Yes. Any person, including a believer, can have an evil spirit in their body and/or their soul, which is the mind, emotions & will of a person. However, the "spirit" of every human being is reserved exclusively for God to come into & dwell in.
Jesus said, "that which is born of the Spirit is [human] spirit..." [John 3:6] showing that when a person is born again [John 3:7] it is the person's own "spirit" that is birthed by God's Spirit.
But, even a Spirit-filled believer can still have enemy spirits that are influencing & even attached to their body (like cancer or some other physical affliction) or influencing or attached to their mind, emotions or will, hindering advancement in Christ.
Importantly, the Greek word in the New Testament for our English translation of "demon-possessed" has the actual definition as being "demonized". So, whether a person has an evil mindset or is completely taken over by demons who control that person's "will" [Mark 5:1] , then according to Scripture that person is "demonized".
Can a believer be demon-possessed ?
[ Book / 2005 - "The Eyes Have It" / Rob C. / 22
Chapters for Ministers who thirst to cast out
demons, lay hands on others with healings and miracles following their ministry and to "have
their senses trained to discern good and evil"
as Hebrews 5:14 instructs. ]
"Behold, I give you authority over all the power of the enemy; And no thing shall harm you." [ Lord Jesus Christ / Gospel Luke 10:19 ]
Can a believer be demon-possessed ?
D E L I V E R A N C E M I N I S T R Y - T E S T I M O N Y
As former Sr. Pastor of Hosanna Christian Fellowship & as a minister in the Los Angeles Prison system as Associate Chaplain for almost 6 years I saw extreme cases of demon-possession during services I conducted. Approximately 40 separate times I've cast demons out of people with visible manifestations like flopping on the ground, momentary super-human strength, screaming voices coming from both men & women with their mouths locked wide open, eyes fully rolled back, evil cursing, stiffened bodies, foaming at the mouth, etc.. to name just a few. Of the 40 times, approx. 15 of those deliverances occurred in Christian churches where I was ministering. EVERY TIME, without exception, I witnessed God's mighty power like a violent slamming sledge hammer come crashing down upon the evil spirits & driving them out of persons for their deliverance. For every Servant of the Lord who is baptized in the power of the Holy Spirit & is ready & bold against the devil, then that minister will find God's power over-rules every encounter with demon-possession, decisively and with overwhelm- ing violent force, to His glory. ~Rob Conrad / founder Patmos Ministries