After 1928’s Mortalium Animos, you wouldn’t expect such a change of heart in the Catholic church in such a short time. But many exciting things were happening. Brilliant Catholic scholars like Henri de Lubac and Yves Congar, among many others, were taking a fresh look not only at Catholic theology but at its roots in the early church fathers. This was a heritage shared by Catholics, Orthodox, and Protestants—in fact, everyone was taking a fresh look at the past.
A motivation from the opposite direction was the bitter first half of the twentieth century marked by incredibly destructive wars between Christians. Not only was the horror of this “Christian civil war” recognized to be contrary to God’s will, but soldiers and prisoners of war from different churches came to realize in their extreme situations that they shared the same faith after all.
Vatican II’s decree on ecumenism is called Unitatis Redintegratio, “Restoration of Unity,” leaves no doubt about its new positive attitude from its very first paragraph:
“The restoration of unity among all Christians is one of the principal concerns of the Second Vatican Council. Christ the Lord founded one Church and one Church only. However, many Christian communions present themselves to men as the true inheritors of Jesus Christ; all indeed profess to be followers of the Lord but differ in mind and go their different ways, as if Christ Himself were divided. Such division openly contradicts the will of Christ, scandalizes the world, and damages the holy cause of preaching the Gospel to every creature.” (§1)
The tendency toward internal division has existed for along time, and UR admits that there is plenty of guilt to go around:
“Even in the beginnings of this one and only Church of God there arose certain rifts, which the Apostle strongly condemned. 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, men of both sides were to blame. 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 brothers, with respect and affection. For men who believe in Christ and have been truly baptized are in communion with the Catholic Church even though this communion is imperfect… all who have been justified by faith in Baptism are members of Christ’s body, and have a right to be called Christian, and so are correctly accepted as brothers by the children of the Catholic Church.” (§3)
What a change! From being outside the walls and unworthy even of the name Christian, now the baptized outside of the Catholic fold are said to be “in communion” with the Catholic church, “even though this communion is imperfect.” UR even uses that favorite of Lutheran phrases, “justified by faith,” as the qualifier to be a member of Christ’s body.
But even more amazing than this is the acknowledgement of true Christianity not just in individuals—which, as UR says, can’t always help where they’ve been born or what church they’ve been raised in—but also in institutions and structures:
“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… It follows that the separated Churches 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.” (§3)
The Spirit of Christ does work in these churches and communities outside the Catholic Church—and even for salvation. That’s what opens the door to ecumenism.