Those of us who study Roman Catholicism, as well as interact with her apologists, can often be confused by some of the “ecumenical” terminology used post-Vatican II (1962-1965), such as the claim that certain Churches (Eastern Orthodox and many Protestant) groups “subsists in” the Catholic Church. The following is a very good discussion of the theological meaning of this term and how it does not necessarily mean that Catholicism is backing away from its unique truth claims after Vatican II, at least on this score:
Concerning the interpretation of the term subsistit in—which is in fact “the foundational and essential principle upon which ecumenism is based”—it should be explained that the Second Vatican Council effectively recognizes the presence of some elements of holiness and truth in the separated Churches and ecclesial communities, which are, however, “gifts belonging to the Church of Christ” which “constituted and organized as a society in the present world, subsists in the Catholic Church, which is governed by the successor of Peter and by the bishops in communion with him”. It is true therefore to say that all the baptized are “Christians” and “united to Christ”; but fully incorporated into Christ and only those who “accept all the means given to the Church together with her entire organization and who—by the bonds constituted by the profession of faith, the sacraments, ecclesiastical government, and communion—are joined in the visible structure of the Church of Christ, who rules her through the Supreme Pontiff and the bishops”. The replacing of “est” with “subsistit in” has given the impression that the Church has renounced her claim to be the true Church of Christ. In reality, though this is not an abandonment of her traditional claim but rather the Church’s opening to the particular demands of ecumenism and of the separated ecclesial communities. In virtue of the elements of holiness and truth present in such communities, it cannot be denied that they have “a certain ecclesial character. But to be ‘ecclesial’ is not yet to be a ‘Church’.” (Adriano Garuti, Primacy of the Bishop of Rome and the Ecumenical Dialogue [San Francisco: Ignatius Press, 2004], 164)
