The Exotic American Island No One Knows About Photo credit: CC license by Marilyn Sourgose 13. Roman Catholicism is the religion of Guam. Because of the early Spanish-American influence on the island, Roman Catholics comprise upwards of 90% of the Guam population. In Agana, the cultural hub and capital of Guam, there is a gigantic rotating statue of Pope John Paul the 2nd. Prev13 of 17Next From Around The Web Facebook Comments comments