A history lesson begins UR3, and a concession that unity has been an elusive virtue for us Christians:
Even in the beginnings of this one and only Church of God there arose certain rifts,(Cf. 1 Cor. 11, 18-19; Gal. 1, 6-9; 1 Jn. 2, 18-19.) which the Apostle strongly condemned.(Cf. 1 Cor. 1, 11 sqq; 11, 22.) But in subsequent centuries much more serious dissensions made their appearance and quite large communities came to be separated from full communion with the Catholic Church-for which, often enough, (people) of both sides were to blame.
Catholics share blame for divisions.
The children who are born into these Communities and who grow up believing in Christ cannot be accused of the sin involved in the separation, and the Catholic Church embraces upon them as (sisters and) brothers, with respect and affection.
And today’s non-Catholics are not to blame for these divisions.
Let’s weave through the rest of this long section carefully. First, non-Catholics possess a communion with the Catholic Church, though this is acknowleged as imperfect.
For (those) who believe in Christ and have been truly baptized are in communion with the Catholic Church even though this communion is imperfect.
Differences in theology and organized structure obstruct a full communion.
The differences that exist in varying degrees between them and the Catholic Church-whether in doctrine and sometimes in discipline, or concerning the structure of the Church-do indeed create many obstacles, sometimes serious ones, to full ecclesiastical communion.
What is the purpose of the ecumenical movement? Read here:
The ecumenical movement is striving to overcome these obstacles.
People may not be Catholic, but the Church recognizes they are part of Christ’s Body:
But even in spite of them it remains true that all who have been justified by faith in Baptism are members of Christ’s body,(Cf. CONC. FLORENTINUM, Sess. VIII (1439), Decretum Exultate Deo: Mansi 31, 1055 A.) and have a right to be called Christian, and so are correctly accepted as (sisters and) brothers by the children of the Catholic Church.(Cf. S. AUGUSTINUS, In Ps. 32, Enarr. 11, 29: PL 36, 299)
Outside of the Church, one finds God-given gifts and graces which are also seen in the Catholic Church, and which serve to draw people to God:
Moreover, some and even very many of the significant elements and endowments which together go to build up and give life to the Church itself, can exist outside the visible boundaries of the Catholic Church: the written word of God; the life of grace; faith, hope and charity, with the other interior gifts of the Holy Spirit, and visible elements too. All of these, which come from Christ and lead back to Christ, belong by right to the one Church of Christ.
Don’t forget the Catholic regard for the liturgy of separated communities. These too offer believers the opportunity to worship God and be open to the sanctification of grace:
(Those) divided from us also use many liturgical actions of the Christian religion. These most certainly can truly engender a life of grace in ways that vary according to the condition of each Church or Community. These liturgical actions must be regarded as capable of giving access to the community of salvation.
Separated Christians know and experience Christ’s salvation:
It follows that the separated Churches(Cf. CONC. LATERANENSE IV (1215) Constitutio IV: Mansi 22, 990; CONC. LUGDUNENSE II (1274), Professio fidei Michaelis Palaeologi: Mansi 24, 71 E; CONC. FLORENTINUM, Sess. VI (1439), Definitio Laetentur caeli: Mansi 31, 1026 E.) and Communities as such, though we believe them to be deficient in some respects, have been by no means deprived of significance and importance in the mystery of salvation. For the Spirit of Christ has not refrained from using them as means of salvation which derive their efficacy from the very fullness of grace and truth entrusted to the Church.
And in conclusion, the Catholic Church is said to offer something “all-embracing” to believers:
Nevertheless, our separated (sisters and brothers), whether considered as individuals or as Communities and Churches, are not blessed with that unity which Jesus Christ wished to bestow on all those who through Him were born again into one body, and with Him quickened to newness of life-that unity which the Holy Scriptures and the ancient Tradition of the Church proclaim. For it is only through Christ’s Catholic Church, which is “the all-embracing means of salvation,” that they can benefit fully from the means of salvation. We believe that Our Lord entrusted all the blessings of the New Covenant to the apostolic college alone, of which Peter is the head, in order to establish the one Body of Christ on earth to which all should be fully incorporated who belong in any way to the people of God. This people of God, though still in its members liable to sin, is ever growing in Christ during its pilgrimage on earth, and is guided by God’s gentle wisdom, according to His hidden designs, until it shall happily arrive at the fullness of eternal glory in the heavenly Jerusalem.
The section ends on a note of optimism, that the Church experiences progress, the progress of growth in grace, during our earthly existence. There is the hope that divided Christianity will grow and collectively cone to its senses regarding the quality of unity. This section is significantly nuanced: setting out the Catholic position strongly, linking it to the ministry of Peter, but acknowledging the action of God outside of the Catholic Church.