The Man Who Would Be Ratzinger

When he was Joseph Cardinal Ratzinger, Pope Benedict XVI was known as the hard-line enforcer of church doctrine for John Paul II. But the man the new Pontiff has just named to fill his old job, prefect of the Congregation for the Doctrine of the Faith, is harder to pin down.

San Francisco Archbishop William J. Levada is, for one thing, the first American ever to reach such an influential position in the Roman Catholic hierarchy. A native of Long Beach, California, who headed the diocese in Portland, Oregon, before moving to San Francisco in 1995, he is...