Final answer:
The predominant religion in West New Guinea (part of Indonesia) is Islam, while East New Guinea (Papua New Guinea) is predominantly Christian, with a presence of indigenous (folk) religions.
Step-by-step explanation:
The question asks about the predominant religions of New Guinea, which is divided between Indonesia (West New Guinea) and Papua New Guinea (East New Guinea). In Indonesia, including West New Guinea, the most widely practiced religion is Islam. However, in Papua New Guinea, Christianity is the primary religion, with a mix of Roman Catholicism, Evangelical Lutheran, and other Christian denominations. Additionally, there are also many who practice indigenous (folk) religions throughout the region.