On a warm summer evening several years ago, congregants jammed the front of the Tabernacle Church of God in LaFollette, Tennessee. It was homecoming time, and scores of Pentecostals, hailing from throughout Appalachia, had gathered to worship God in a ritual that risked bodily harm.

Dancing around the pulpit, Tyler Evans, whose family has handled serpents for five generations, held a Coke bottle with a flaming wick to his skin, a practice called “handling fire.” The teenager suffered no burns. Next, he took a swallow from a Mason jar containing a mixture of water and strychnine—a bitter poison made famous in Agatha Christie novels. He let out nary a cough. From a few feet away, Pastor Andrew Hamblin nodded in