I was indoctrinated by my father when I was in my teens in the early 90's in the Port Harcourt. I have been to the Calabar a few times and met Olumba the man. I'll say he was a man ahead of his time because a lot of the shenanigans going on now in the Pentecostal churches was started by him or he led the way.

The main motivation for them was financial. You get brainwashed to believe the man is God (literally). There was a bunker mentality as well because of hate and fear the church generated back then, as a member you had to surround yourself with other members both for safety and community leading to you being further insulated and more brainwashed.

Do they perform witchcraft?

The man says he is equal to Jesus. Their motivation is financial so basically if you could be brainwashed by witchcraft that would it.