One day, Roger Mahony, then about 12, was working in his father's poultry processing plant in the San Fernando Valley when law enforcement agents searching for illegal immigrants raided the facility. "I will never forget them bursting through the doors," Mahony recalled. "I was terrified by it. And I thought, 'These poor people; they're here making a living supporting their families.' . . . It had a very deep impact on me throughout the years." One of his father's workers was taken away. Now Cardinal Roger Mahony, he leads the Archdiocese of Los Angeles. It is the largest Roman Catholic...