In the past several years, two battered cottonseed silos in Waco, Texas, surrounded by food trucks selling sweet tea and energy balls, have become a pilgrimage site for Christian homemakers from around the country, among others. The silos form part of an open-air mall erected by Chip and Joanna Gaines, the husband-and-wife stars of "Fixer Upper: Welcome Home," a popular reality show. The Gaineses have built a commercial empire called Magnolia, by selling the trappings of a trendy, Christian life style. In 2017, a market-research blog found that they were some of the most popular celebrities among faith-based consumers. One afternoon in May, Beth Allison Barr, a medieval-history professor at Baylor University, who studies the role of women in evangelical Christianity, visited the store on a kind of research trip. We walked past a line of hungry tourists waiting outside a bakery that sells pastel-frosted cupcakes, and by boxwood hedges studded with lavender. "It's like Waco's Disneyland," Barr said. "We evangelicals love it."