"Not only did the Savior command that all nations should enter the Church, but He also decreed the Church to be a means of salvation without which no one can enter the kingdom of eternal glory."
I read through the web link you posted. I think your definition of "Church" is not the same as what the link defines it. Again, the Roman Catholic Church is not the entirety of the definition "Church" when it is defined in your link, or Vatican 2.
We agree that the Church is necessary for salvation. However, it is clear from Scripture and Tradition that Baptism is the entry by which one becomes a member of the Church. I would ask you to consider the Re-Baptism disagreements during Cyprian's time. You will find that here, we see the Church considered those Baptized by Donatists were not required to be re-baptized to come back into full communion with the Catholic Church. I believe that this gives us insight into the mind of WHAT is the Church. Apparently, the Catholic Church found that those baptized by Donatists were already within the Church, though not fully, as a result of their Donatist Baptism.
In paragraph 15 of the Constitution on the Church, it says that those called to be Christians in other churches and with whom the pope is not yet fully united are nonetheless linked to the Church in many ways, united to Romans Catholics by Scripture, prayer, charity, and even sacraments. In paragraph 16, it even goes on to state that those who seek God whatsoever, if they are good and true, are also related to God's people (Church). ONLY those who persist in darkness and cultivate despair have cut off their relationship to the People of God. I think your definition of "Church" is too narrow. The Roman Church itself does NOT say that one must be a Roman Catholic to go to heaven.
Baptism, even implicit Baptism by desire, has been the means of entry into the Church since the very beginning. This does not mean that the Catholic Church is not necessary - it is the visible sacrament of unity among God's people. However, nowhere have you shown that one must be on the roles of a Roman Catholic diocese to enter heaven. Feeney was wrong, as Pius clarified.
Regards
To suppose that the Catholic Church and the "Church" are not identical would be a grave mistake. Certainly the Holy Office in 1949 would not have thought so!:
"The practice of the Church has always been the same, as is shown by the unanimous teaching of the Fathers, who were wont to hold as outside Catholic communion, and alien to the Church, whoever would recede in the least degree from any point of doctrine proposed by her authoritative Magisterium. Epiphanius, Augustine, Theodoret, drew up a long list of the heresies of their times. St. Augustine notes that other heresies may spring up, to a single one of which, should any one give his assent, he is by the very fact cut off from Catholic unity" (Leo XIII, Satis Cognitum, §9).
"If we would define and describe this true Church of Jesus Christ - which is the One, Holy, Catholic, Apostolic and Roman Church - we shall find nothing more noble, more sublime, or more divine than the expression 'the Mystical Body of Christ'" (Pius XII, Mystici Corporis Christi, §13)
"Some say they are not bound by the doctrine, explained in Our Encyclical Letter of a few years ago, and based on the Sources of Revelation, which teaches that the Mystical Body of Christ and the Roman Catholic Church are one and the same thing" (Pius XII, Humani Generis, §27)
Vatican II concurs, saying:
"Christ, the one Mediator, established and continually sustains here on earth His holy Church, the community of faith, hope and charity, as an entity with visible delineation through which He communicated truth and grace to all. But, the society structured with hierarchical organs and the Mystical Body of Christ, are not to be considered as two realities, nor are the visible assembly and the spiritual community, nor the earthly Church and the Church enriched with heavenly things; rather they form one complex reality which coalesces from a divine and a human element" (LG 8)
Note that the footnote following this statement is to Humani Generis - so the Council makes Pius' teaching its own. The statements about relationship you refer to are just that - relationships. LG 8-13 are very clear that the "People of God", or the Church, is composed only of the faithful, in accordance with the traditional definition of the Church as the "congregation of the faithful, subject to lawful pastors" (thus St. Robert Bellarmine).
To make the relationships the determination of the Church would be absurd - as the Council says, "And there belong to or are related to it in various ways, the Catholic faithful, all who believe in Christ, and indeed the whole of mankind". I say rather that the Church is composed only of the Catholic faithful: "Actually only those are to be included as members of the Church who have been baptized and profess the true faith, and who have not been so unfortunate as to separate themselves from the structure of the Body, or been excluded by legitimate authority" (Pius XII, Mystici Corporis Christi, §21), who are the only ones "fully incorporated in the society of the Church" (LG 14). If we should speak of the catechumens, or others in an analogous position (believing in the Catholic Faith inasmuch as they can, and infused by faith, hope, and charity), they are not properly speaking parts or members of the Church, since they do not belong bodily: "Actually only those", etc., although they do belong spiritually, since they are sons of God and therefore also of the Church which is the Mystical Body, in spirit although not in body: thus St. Augustine says that catechumens are conceived in the womb of the Church, but not yet sons. This is the distinction made by St. Robert Bellarmine in the De Ecclesia Militante, and by Cardinal Journet in the following words, which I embrace as my own: "Above all, we must not say that the just 'without' belong to the invisible Church. Say rather, if you will, that they belong invisibly to the visible Church."
However, it is clear from Scripture and Tradition that Baptism is the entry by which one becomes a member of the Church
Most true - for those baptized into the Catholic Church. But otherwise: "And if it is mere madness to assert this, then let them confess that a man can be baptized with the true baptism of Christ, and that yet his heart, persisting in malice or sacrilege, may not allow remission of sins to be given; and so let them understand that men may be baptized in communions severed from the Church, in which Christ's baptism is given and received in the said celebration of the sacrament, but that it will only then be of avail for the remission of sins, when the recipient, being reconciled to the unity of the Church, is purged from the sacrilege of deceit, by which his sins were retained, and their remission prevented" (St. Augustine, On Baptism, Against the Donatists, I, 12:18). This is why Pius XII states that not only true baptism, but also profession of the true faith and adherence to the structure of the Body is necessary for membership in the Church.
nowhere have you shown that one must be on the roles of a Roman Catholic diocese to enter heaven
I should hope not, since I don't believe it! The letter of the Holy Office summarizes my understanding of this matter: "Therefore, that one may obtain eternal salvation, it is not always required that he be incorporated into the Church actually as a member, but it is necessary that at least he be united to her by desire and longing".