The Papacy and Christian Unity
As Vicar of Jesus Christ, the Pope governs the Catholic Church as its supreme head. The Pope, as Bishop of Rome, is the chief Pastor and shepherd of the whole Church. We believe that the Pope is the successor of Saint Peter, and his bishops are successors of the Twelve Apostles.
It is clear throughout that it is a question of the bishops acting in conjunction with their
head, never of the bishops acting independently of the Pope. In the latter instance, without
the action of the head, the bishops are not able to act as a College: this is clear from the
concept of "College." This hierarchical communion of all the bishops with the Supreme
Pontiff is certainly firmly established in Tradition. (Lumen Gentium, Note of Explanation)
In the Acts of the Apostles, we come to know Peter is the head of the early Church. When Peter is given the "keys to the Kingdom," Christ is establishing the divine office of leadership over the Church. The permanence of the office of the Pope is essential to the everlasting nature of the Church.
"The Roman Pontiff, head of the college of bishops, enjoys this infallibility in virtue of his
office, when, as supreme pastor and teacher of all the faithful - who conforms his brethren in
the faith - he proclaims by a definitive act a doctrine pertaining to faith or morals ... The
infallibility promised to the Church is also present in the body of bishops, when, together
with Peter's successor, they exercise the supreme Magisterium," above all in an Ecumenical
Council. When the Church through its supreme Magisterium proposes a doctrine "for belief
as being divinely revealed," and as the teaching of Christ, the definitions "must be adhered
to with the obedience of faith." This infallibility extends as far as the deposit of divine
Revelation itself. (CCC891)
Divine assistance is also given to the successors of the Apostles, teaching in communion with
the successor of Peter, and, in a particular way, to the Bishop of Rome, pastor of the whole
Church, when, without arriving at an infallible definition and without pronouncing in a
"definitive manner," they propose in the exercise of the Ordinary Magisterium a teaching
that leads to better understanding of Revelation in matters of faith and morals. To this
ordinary teaching the faithful "are to adhere to it with religious assent" which, though
distinct from the assent of faith, is nonetheless and extension of it. (CCC892)
Unity is essential for the followers of Jesus Christ. Saint John's Gospel reminds us, "The glory which You have given Me I have given to them, that they may be one, just as We are One; I in them and You in Me, that they may be perfected in unity, so that the world may know that You sent Me, and loved them, even as You have loved Me" (John 17:22-23).
The Catholic Church is united under the leadership of the Bishop of Rome, the Pope. Historical breaks and schisms have left us fractured with the Eastern Orthodox churches no longer in full unity with Roman Catholicism. Beginning with Pope John XXIII and continuing through the papacies of John Paul II, Benedict XVI, and Francis I, the movement to come together in full Christian unity has been underway.