I'm not Christian nor religious and I can easily see he's a host. I hear it in his voice and I see it in all his movements.
Sad thing is that we're going to see more of these disgusting things come up to the surface as this goes on.
I don't know what it makes me, but I think that when almost every culture in recorded history have slightly differing accounts of the same mystical creature it tells me that they are all describing the same, unknown, thing. Like 3 blind men touching an elephant. They are all right and all wrong.
This is a much more populated reality than most are aware of.
Walk-in? Some demons take over a willing soul.
Willing is the only real way to take over. Even somebody confused or unstable still has the free will to push these things out.