SPINDALE, N.C. — When Andre Oliveira answered the call to leave his Word of Faith Fellowship congregation in Brazil to move to the mother church in North Carolina at the age of 18, his passport and money were confiscated by church leaders — for safekeeping, he said he was told. Trapped in a foreign land, he said he was forced to work 15 hours a day, usually for no pay, first cleaning warehouses for the secretive evangelical church and later toiling at businesses owned by senior ministers. Any deviation from the rules risked the wrath of church leaders, he said,...