In number 8 of the Dogmatic Constitution Lumen gentium ‘subsistence’ means this perduring, historical continuity and the permanence of all the elements instituted by Christ in the Catholic Church, in which the Church of Christ is concretely found on this earth.
It is possible, according to Catholic doctrine, to affirm correctly that the Church of Christ is present and operative in the churches and ecclesial Communities not yet fully in communion with the Catholic Church, on account of the elements of sanctification and truth that are present in them. Nevertheless, the word “subsists” can only be attributed to the Catholic Church alone precisely because it refers to the mark of unity that we profess in the symbols of the faith (I believe… in the “one” Church); and this “one” Church subsists in the Catholic Church.
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RESPONSES TO SOME QUESTIONS REGARDING CERTAIN ASPECTS OF THE DOCTRINE ON THE CHURCH