One of the strangest encounters I had at a church was a man who had joined at least four different groups. He had been a JW, a Mormon, a Pentecostal, and he was at a Seventh-day Adventist Church when I met him. He said he left the JWs because they were anti-semitic, which I found surprising. He claimed he was at a Watchtower that was shamefully bashing Jews. He said the Mormons wanted his credit card details as soon as he got baptised and he never went back. And he said the Pentecostals were demonic.
Groups I’ve not yet visited that I’d like to visit:
Bible Students (if any can be found)
Salvation Army
Coptic
Orthodox
Lutheran
And I forgot on the above list that I visited the New Apostolic Church too, a strange cultic church that is strong in Germany and parts of Africa whose dubious claims to fame are that they supported the Nazis in the Third Reich and predicted the end of the world in the 1950s.