Before contact with Europeans, Chamorro makanas, or shamans, helped facilitate contact between the living and the spirits of the ancient known as taotaomo'na.
By the second half of the 17th century, Guam would begin to be settled by Spaniards and the missionaries who accompanied them. The Chamorro culture which had developed over thousands of years underwent rapid transformation. Among the changes were shifts in faith practices. The Spanish brought new ways of worshipping and introduced Roman Catholicism to the island.
Over 85 percent of Guam's population is Roman Catholic. The island is home to over two dozen Catholic churches, including one in each of Guam's 19 villages. Some of these churches are excellent examples of the Spanish-influenced architecture seen around Guam.
Guam also has at least seven Baptist churches, including in the villages of Agana Heights, Upper Tumon, Tamuning, Dededo, Barrigada, Chalan Pago, and Mongmong.
There are multiple Episcopal and Bahai'i houses of worship on the island, as well as Presbyterian, Filipino Christian, Nazarene, Lutheran, and nondenominational churches. Guam's religious population also includes Jehovah's Witnesses.