By Cindy Wooden • Catholic News Service • Posted May 1, 2013

VATICAN CITY (CNS) — The unity of the Catholic Church rises or falls to the degree that its members uncompromisingly hold firm to the faith transmitted by the apostles, said Archbishop Gerhard Muller, prefect of the Congregation for the Doctrine of the Faith.

The congregation helps the pope “promote and safeguard the faith of the simple and, at the same time, strengthen the visible unity of the church,” he said, because “these two tasks are inseparably linked; they hold, stand or fall together.”

Archbishop Muller spoke about the work of the doctrine congregation at a Mass with congregation staff members April 30, the feast of St. Pius V, patron saint of the congregation.

St. Pius, who was pope from 1566 to 1572, “sought to strengthen the unity of the faith through the reform and unification of the liturgy,” the archbishop said. “And still today one can celebrate the Eucharist with his Missal,” which is the basis for the extraordinary or so-called Tridentine Mass.

The Tridentine Mass fell out of use amid the reforms that followed the Second Vatican Council of 1962-65; but in 2007, Pope Benedict XVI lifted most restrictions on its celebration in an effort to reconcile with the disaffected traditionalists.

The future Pope Pius grew up in a humble family in northern Italy and spent much of his childhood in the fields, caring for his family’s sheep.

“Perhaps it was in those years that he began developing an inclination for silence and prayer, a particular sensitivity to the beauty of nature,” an appreciation of simplicity and “a vigilant readiness to care for his flock. And who knows if, watching the flock entrusted to him, he could ever have imagined that the Lord would entrust him with a very different flock.”

The future Pope Pius V entered the Dominican order and was ordained a priest. His years with the sheep, the archbishop said, were “a quiet and humble preparation for important events that would see him take a key role in the church of his time, first as an inquisitor and then as pontiff.”

Pope Pius’ concern was “most of all to protect the faith of the simple both in doctrine and in discipline. He defended the church and the good of the Christian people with all his strength,” the archbishop said, and he led the efforts to put into practice the teachings of the Council of Trent, which was held from 1545 to ’63.

“Pius V was a tenacious upholder of both the faith and church unity,” the archbishop said. “He not only worked to defend the integrity of the faith from heresies,” he also worked for the unity of the church of the East and West by recognizing four great theologians of the Greek tradition — Sts. John Chrysostom, Basil the Great, Gregory of Nazianzus and Athanasius — as doctors of the church alongside Sts. Ambrose, Jerome, Augustine and Gregory the Great.

Promoting the integrity of the faith and the unity of the church are key tasks for the pope, Archbishop Muller said, and helping the pope do that is the job of the doctrinal congregation.

Pope Pius “was not willing to negotiate the faith because he knew that any compromise of the faith of the apostles would be a direct threat to that gift which Jesus prayed for so much and for which he offered his life: the unity of his disciples,” the archbishop said.

“Where the faith of the apostles is alive and where the visible unity of the church is realized, witnesses are born” who naturally share the Gospel with others, he said. “When faith and unity are real, charity and a missionary impulse increase as well.”