Keeper of the Straight and Narrow: JOSEPH CARDINAL RATZINGER

The world's most powerful Cardinal lives a stone's throw from St. Peter's Square, above the terminus of the No. 64 bus, a line infamous for pickpockets. Each morning he sets off on foot at a brisk pace, crossing over cobblestones to arrive at 9 a.m. at the palazzo that once bore the title of the Roman and Universal Inquisition. Soft-spoken and courteous, Joseph Cardinal Ratzinger, 66, looks too benign to be an inquisitor. But his Congregation for the Doctrine of the Faith is the Roman Inquisition's latest incarnation, and as the Catholic Church's chief enforcer of dogma, the Cardinal stands in...