Papua New Guinea holds more than eight hundred languages, which is the highest linguistic density on earth, and a comparable density of distinct religious traditions. It is also almost entirely Christian by affiliation, mostly Catholic, Lutheran, United Church, Anglican, Seventh day Adventist and, increasingly, Pentecostal. Both statements are true at once, and understanding the country requires holding them together rather than treating the second as having replaced the first.
Church membership is near universal and ancestor and spirit practice continues under and alongside it. Ground is owned by clans and carries obligations to the dead who are in it; illness and death are commonly attributed to a cause rather than to chance; and the ritual cycles attached to initiation, exchange and mortuary obligation continue in many places with church participation rather than in opposition to it.
The Sepik river region produced one of the best documented ritual complexes in Melanesia. The haus tambaran, the spirit house, is a large ceremonial building holding carved figures, flutes and masks associated with clan spirits, and initiation cycles conducted in and around it were long and physically demanding. Much of the carving that reached Western museums came out of these buildings, in circumstances that ranged from purchase to removal.
The wider region gave anthropology two of its central categories: the big man, whose authority is built through the redistribution of wealth rather than inherited, and the cargo movement, in which ritual is directed at obtaining the manufactured goods that arrived with outsiders.
A constitutional amendment passed in 2024 declares Papua New Guinea a Christian country.