Every year, crowds fill the streets of the central Mexican town of Atlixco on the Catholic holiday of Good Friday to witness the sight. Throngs of half-naked men walk through the scorching streets blindfolded, toting 70-pound chains and pieces of cactus lodged in their arms and legs. Since 1990, the share of Mexicans who identify themselves as Catholic has dropped from just over 90% to 78%, according to Mexico’s 2020 census.