In this book, Kenneth Nehrbass examines the interaction between traditional or animistic religion (called kastom) and Christianity in Vanuatu. First, he briefly outlines major anthropological theories of animism, then he examines eight aspects of animism on Tanna Island and shows how they present a challenge to Christianity. He traces the history of Christianity on Tanna from 1839 to the present, showing which missiological theories the various missionaries were implementing. Nehrbass wanted to find out what experiences in the lives of the islanders distinguished those who left traditional religion behind from those who held on to it. In the end, he contends that there are twenty factors of gospel response and cultural integration that determine whether an animistic background believer will be a mixer, separator, transplanter, or contextualizer.