Church of Rome, Mithras, and Isis?
Dr. Thiel is in Vatican City and points to a variety of symbols and displays there and explains where some of them seem to have originated from. Specifically, he discusses the connection of the cave grotto and mitre to Mithraism as well as obelisks and certain other ties to Isis. He also briefly touches on some doctrines that those groups share.
Two articles of possibly related interest may be Do You Practice Mithraism? (http://www.cogwriter.com/christianity-mithraism.htm) and Was Jesus Born in the Grotto of the Nativity? (http://www.cogwriter.com/jesus-born-in-a-cave.htm).