Grant Wacker, associate professor of religious history at Duke University, grew up in a Pentecostal home. As he expanded his educational horizons, he moved away from his Pentecostal upbringing and joined the somewhat more moderate United Methodist Church. His roots, nevertheless, are to an extent planted firmly in his early exposure to Pentecostalism.
In Heaven Below: Early Pentecostals and American Culture, a very carefully and fully researched study that is at once historical, sociological, and anthropological, Wacker relates with insight and considerable critical acumen the intriguing story of how an upstart religion gained extraordinary popularity in the last years of the nineteenth century and went on in the twentieth century to claim over twenty million members.
The four major foundations of Pentecostalism are personal salvation, Holy Ghost baptism, divine healing, and the expectation that Christ will soon return to earth. Holy Ghost baptism is sometimes accompanied by speaking in tongues. Wacker presents intriguing case studies of four Pentecostals who went into ecstatic states, collapsed, their bodies twitching, and spoke in tongues, presumably mystically speaking the languages of Indian groups or others who, in the eyes of the faithful, needed missionaries to lead them to God. Wacker approaches such accounts with respect but with a healthy skepticism, pointing out that reports of them were purely anecdotal, related before the age of tape recorders and other technological devices indispensable to modern linguists. Wacker calls much Pentecostal behavior extremely pragmatic, motivated by how people outside the faith view it.
This is a compelling study, providing a useful index and extensive documentation.