No he doesn't give a clear scripture showing that believers can be so bound and demonized.
He posted the verse below which doesn't strongly indicate it was an actual believer in the first place.
Let me ask why Scripture commands us to test spirits within us unless we can get an evil one?
Beth, a personal friend, attends the 1st Baptist church of Naples, FL., was counseling a young Baptist lady named Rachel who was in spiritual turmoil so Beth called me for advice. It seems Rachel was kneeling at the mourners bench one Sunday evening when a woman walked up behind her, laid hands on her and said, “Rachel, you will now speak in tongues” and sure enough Rachel did. Here is Beth's account of what happened next:
“Rachel loves the Lord, reads her Bible every day, and could speak in tongues at will. I asked Rachel if she had ever had her "tongue" spirit tested as commanded by 1John 4:1-3: (excerpts) . . .
"Beloved, believe not every spirit, but try the spirits whether they are of God . . . Hereby know ye the Spirit of God: Every spirit that confesseth that Jesus Christ is come in the flesh is of God: And every spirit that confesseth not that Jesus Christ is come in the flesh is not of God, and this is the spirit of the Antichrist . . .”
Rachel conceded that she never had her spirit tested like that, but would like to have it done. We met a couple of days later in a prayer room at the church. After a short time of prayer, I asked Rachel to start speaking in tongues.
While Rachel was doing so, I said in a quiet voice, "Spirit, in the name of the Lord Jesus, declare Jesus Christ is come in the flesh." This spirit did not respond directly, but Rachel started speaking louder in tongues.
Again I said, "Spirit, in the name of the Lord Jesus, declare Jesus Christ is come in the flesh." Again, this spirit did not acknowledge Jesus.
Now does it not strike you as strange, that a spirit (supposedly God's Holy Spirit) would not confess Jesus? It did me. So I said, "Don't you see, Rachel, that this spirit cannot be of the Lord? It refuses to confess Jesus."
To which Rachel replied, "But in my mind this spirit is saying, 'I am lord.' "
I was almost deceived by that declaration, but I had just called ES, an elder, to discuss my meeting with Rachel when he warned me that demons are cunning, and could say something like that. So·I pressed Rachel’s spirit with, "Spirit, are you the Lord who died on the Cross, was buried, rose on the third day, and now sits at the right hand of Authority on high?"
The spirit within Rachel shrieked out, "Nooooo!" Rachel's face contorted, and hissing and snarling, she fell off her chair. Her hands twisted into unnatural claw-like shapes. She curled into a fetal position and whimpered, "Please help me get rid of this thing." I phoned two friends experienced in deliverance and asked them to come assist me, and within an hour or so Rachel was completely free of that demon.
Are we now going to claim that Rachel wasn’t really a Christian or that her familiar spirit wasn’t really a demon? Please don’t make me laugh. I know those people personally; they weren’t lying and neither am I.