From the late eighteenth century the Pacific became the most intensively missionised region on earth relative to its population, and the pattern of conversion followed the shape of the societies concerned.
Where authority was concentrated in chiefs, conversion tended to be rapid and collective, because religion and rank were the same structure and a ruler's decision carried the population. Where it was dispersed, as in much of Melanesia, missions worked village by village over generations. Both London Missionary Society Protestants and Catholic orders operated across the ocean, sometimes in direct competition, and Pacific Islanders themselves became the majority of the mission workforce, travelling from Tahiti, Samoa, Tonga and Fiji to islands further west.
The twentieth century brought two further disruptions of religious consequence. The Pacific War turned dozens of islands into battlefields and brought enormous quantities of foreign goods and personnel, which is part of the background to the movements outsiders labelled cargo cults, a term the atlas records as contested and unhelpfully broad. Nuclear testing in the Marshall Islands and French Polynesia from 1946 displaced communities from atolls understood as ancestral ground and contaminated others, and churches were among the principal organisers of the protest.
The ocean's societies today are overwhelmingly Christian and among the most religiously observant anywhere, while older categories remain in active use in land tenure, funerary practice and the treatment of particular places.