1. Pope Pius XII, "Mystici Corporis" (1943):6. Congretation for the Doctrine of the Fatih, "Responses to Some Questions Regarding Certain Aspects of the Doctrine on the Church" (June 29, 2007):
The "true Church of Jesus Christ ... is the One, Holy, Catholic, Apostolic and Roman Church." [Litt. Enc. Mystici Corporis Christi, A.A.S., vol. XXXV, p. 193 sq.; citing Vat. Council, Const. de Eccl., Const. de fide cath., c. 1.; emphasis added.]2. Pope Pius XII, "Instruction on the Ecumenical Movement" (1949):
"[The Bishops] must restrain that dangerous manner of speaking which generates false opinions and fallacious hopes incapable of realization; for example, to the effect that the teachings of the Encyclicals of the Roman Pontiffs on the return of dissidents to the Church, on the constitution of the Church, on the Mystical Body of Christ, should not be given too much importance seeing that they are not all matters of faith, or, what is worse, that in matters of dogma even the Catholic Church has not yet attained the fullness of Christ, but can still be perfected from outside. . . .3. Pope Pius XII, "Humani Generis" (1950):
Therefore the whole and entire Catholic doctrine is to be presented and explained: by no means is it permitted to pass over in silence or to veil in ambiguous terms the Catholic truth regarding ... the constitution of the Church, the primacy of jurisdiction of the Roman Pontiff, and the only true union by the return of the dissidents to the one true Church of Christ." [emphasis added]
". . . the Mystical Body of Christ and the Roman Catholic Church are one and the same thing." [para. 27; emphasis added.]4. Vatican II Dogmatic Constitution on the "Lumen Gentium," promulgated by Pope Paul VI (1964):
"[The] Church constituted and organized in the world as a society, subsists in the Catholic Church, which is governed by the successor of Peter and by the Bishops in communion with him . . ." [para. 8, citing: Pius XII, Const. Apost. Munificentissimus, 1 no. 1950: AAS 42 (1950) ú Denz. 2333 (3903). Cfr. S. Io. Damascenus, Enc. in dorm. Dei gcnitricis, Hom. 2 et 3: PG 96, 721-761, speciatim col. 728 B. - S. Germanus Constantinop., in S. Dei gen. dorm. Serm. 1: PG 98 (6), 340-348; Serm. 3: col. 361. - S. Modestus Hier., In dorm. SS. Deiparae: PG 86 (2), 3277-3312; emphasis added.]5. Avery Cardinal Dulles, Vatican III: The Work That Needs to Be Done, ed. by David Tracy with Hans Kueng and Johann Metz (New York: Concilium, Seabury Press, 1978):
"The Church of Jesus Christ is not exclusively identical to the Roman Catholic Church. It does indeed subsist in Roman Catholicism, but it is also present in varying modes and degrees in other Christian dommunities to the extent that they too are what God initiated in Jesus and are obedient to the inspirations of Christ's Spirit. As a result of their common sharing in the reality of the one Church, the several Christian communities already have with one another a real but imperfect communion." [p. 91; emphasis added.]
Second Question: What is the meaning of the affirmation that the Church of Christ subsists in the Catholic Church?It's one thing to be accurate in every minute detail. It's another thing to be clear and avoid confusing the faithful. The two are not always comfortable bedfellows.
Response: "Christ 'established here on earth' only one Church and instituted it as a 'visible and spiritual community' . . ."
". . . ‘subsistence’ means this perduring, historical continuity and the permanence of all the elements instituted by Christ in the Catholic Church . . ."
"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. . . ."
Third Question: Why was the expression “subsists in” adopted instead of the simple word “is”?
Response: "The use of this expression, which indicates the full identity of the Church of Christ with the Catholic Church, does not change the doctrine on the Church. Rather, it comes from and brings out more clearly the fact that there are 'numerous elements of sanctification and of truth' which are found outside her structure, but which 'as gifts properly belonging to the Church of Christ, impel towards Catholic Unity.'" [Lumen Gentium, 8.2]
"'It follows that these separated churches and Communities, though we believe they suffer from defects, are deprived neither of significance nor importance in the mystery of salvation. In fact the Spirit of Christ has not refrained from using them as instruments of salvation, whose value derives from that fullness of grace and of truth which has been entrusted to the Catholic Church'" [Second Vatican Council, Decree Unitatis redintegratio, 3.4.].