At the beginning of April 2005, the Catholic Church faced a difficult question: Who could possibly succeed Pope John Paul II? Cardinal Joseph Ratzinger, previously thought too old, was elected, the most worthy available successor, even if he insisted that after the “great pope” he was only a “humble worker in the vineyard.” Humble but most formidable.

Who, then, would succeed Ratzinger as prefect of the Congregation for the Doctrine of the Faith (CDF)? That was in some ways an even more difficult question.

There was literally no candidate who could do what Cardinal Ratzinger had done. The most gifted bishop-theologian of his generation, Cardinal Ratzinger could not be replaced. There was speculation that the new pope, Benedict XVI, would reach into the same world of theological scholarship whence he came, but who?

When Archbishop William Levada of San Francisco was chosen as the new CDF prefect in May 2005, there was widespread surprise. He was astute, but not a scholarly academic. And he was an American! The highest-ranking American in the history of the Roman Curia, it would turn out, at a time when the prestige of the CDF — La Suprema as it was once known in Rome — was at its peak.

Benedict XVI had no need of a theological adviser at the CDF; he could handle that on his own. But his 24 years of service there made him aware of two critical priorities: the importance of the CDF in ensuring that the Roman Curia as a whole thought theologically and the priority of the CDF in dealing with sexual-abuse cases. Cardinal Levada could attend to both tasks.

When, less than a year later, the case against Father Marcial Maciel — the fraudulent, corrupt and wicked founder of the Legionaries of Christ — was brought to a successful conclusion, it demonstrated that Cardinal Levada could do the second task. He would continue what his predecessor had started.

In 2010, Levada would strengthen the legal provisions for sexual abuse brought in under St. John Paul II and Cardinal Ratzinger in 2001, and the CDF would mandate reporting to civil authorities.

The great example of helping the Curia to think theologically, rather than bureaucratically or even politically, was the establishment of the “personal ordinariates” for former Anglicans who wished to become Catholics that was accomplished during Cardinal Levada’s tenure. It was a generous and creative ecumenical gesture, allowing groups of Anglicans to enter into full communion with Rome while maintaining their distinctive Anglican patrimony.

Perhaps Cardinal Levada’s papers might be posthumously researched and published so that the fascinating tale of the ordinariates might be fully told. Suffice it to say that the professional ecumenists in the Roman Curia, led by Cardinal Walter Kasper, the president of the Council for Christian Unity, thought the ordinariates were a bad idea. They might offend the Anglican Communion or perhaps even the Orthodox, who find the existence of diverse rites in the Catholic Church distasteful.

The entire initiative appeared to point in the direction of what the professional ecumenists consider to be the much-loathed “unity of return,” in which Protestants become Catholic, rather than some as-yet-undefined hybrid. Cardinal Levada’s CDF, working with the papal household, got the whole matter done with some deft bureaucratic maneuvering, needed precisely to avoid bureaucratic inertia stifling the movement of the Holy Spirit.

As a legacy gift to the personal ordinariates, Cardinal Levada’s personal secretary while prefect, Steven Lopes, is now their bishop in North America.

How did Cardinal Levada come to Pope Benedict’s attention? He first served as an official in the CDF as a priest from 1976 to 1983, so there was brief overlap with the beginning of Cardinal Ratzinger’s service as prefect. But it was his appointment in 1986 — the same year he was made archbishop of Portland — to the editorial committee of the Catechism of the Catholic Church, that brought him more directly into contact with Cardinal Ratzinger.

Cardinal Ratzinger could assess Archbishop Levada’s work, as one of six bishops on that committee, on one of the most important initiatives of the post-Vatican II period.

In 2010, Cardinal Levada visited Canada, and when addressing Catholic Christian Outreach — a movement similar to Fellowship of Catholic University Students in the United States — he commented upon the importance of the Catechism.

“I conclude with a personal note about our work at the CDF. Much of our work involves identifying problems, correcting errors and disciplining abuses. But we do all that so that we can propose the truth of Jesus Christ. In this we have no better model than my predecessor, our Holy Father. For 24 years he worked vigorously to correct errors, but never lost sight of proposing the truth. Had he never been elected pope, the great achievement of the Catechism of the Catholic Church would itself have stood as a remarkable legacy. Now, even with his heavy burden of administrative duties, the Holy Father teaches brilliantly, proposing the Catholic faith anew.”

Cardinal Levada retired from the CDF at age 76, after seven years of service. His successor was Cardinal Gerhard Müller, a German scholar-bishop who was in charge of publishing Cardinal Ratzinger’s collected works. Though it was not known at the time, in July 2012, the appointment of Cardinal Müller was taken after Pope Benedict had already decided that that he would abdicate. The CDF would need someone in Cardinal Ratzinger’s mold again.

William Levada belonged to a quartet of California priests, all born in 1936, who would go on to have an outsize influence on the Church. Bishop Tod Brown would become bishop of Orange in California, one of the largest dioceses in the nation. Archbishop George Niederauer, one day older than Cardinal Levada and one of his closest friends, would succeed him as archbishop of San Francisco. Cardinal Roger Mahony of Los Angeles would be the other cardinal in the group.

The four clerical careers crossed paths, and occasionally ecclesiastical positions, too.

When appointed archbishop of San Francisco in 1995, Levada was asked whether he expected to be created a cardinal at a news conference.

“There is only one cardinal in California,” he said at a time when Los Angeles, the largest diocese in the country, was still considered a cardinalatial see. “He is in Los Angeles. Being a cardinal is the consolation prize for not being the archbishop of San Francisco.”

Cardinal Levada would be awarded other prizes in due course. May he now enjoy the consolation of a merciful judgment and the company of the saints.

Father Raymond J. de Souza is editor in chief of Convivium magazine.