When Pope Francis canonizes Father Junípero Serra on Wednesday in Washington, D.C., Serra will be the first Hispanic American saint, and the first saint canonized on American soil. He also figures to be one of the most controversial saints in the long history of the Roman Catholic Church – a symbol that roils some hearts even as it lifts others. Serra, an 18th-century Spanish friar who founded nine of the 21 California missions, including Mission San Juan Capistrano, is gaining sainthood, in part, because he helped bring the church to the Americas. By one reckoning, Serra’s legacy is nothing less...