One Sunday late last summer, I saw a sign on the side of the road in Adelphi, Md. It was small, wedged between dozens of presidential campaign signs, and it was in Spanish: Iglesia de Dios del Evangelio Completo. Down the road I found another sign: Primera Iglesia Bautista Hispana de Maryland. Soon I started seeing signs for Protestant Latino churches everywhere. There was even one right behind my apartment in Virginia. And so I decided to visit two of the largest Latino Protestant churches in the area—La Roca de la Eternidad in Adelphi and Iglesia Cuadrangular el Calvario in nearby Silver Spring.
What I discovered signaled a Latino Reformation. Both churches were doubling in size every few years. Many of the congregants were Catholic converts, and even more may have been undocumented. All were fervent believers—they sang with hands high, danced during worship, and often brought their own...