Over the course of the last 150 years, the magisterium has made it very clear how the teaching “there is no salvation outside the Church” is to be understood. I will present the major explanations over the next few posts.
(Quanto Conficiamur Moerore, Pius IX) “Here, too, our beloved sons and venerable brothers, it is again necessary to mention and censure a very grave error entrapping some Catholics who believe that it is possible to arrive at eternal salvation although living in error and alienated from the true faith and Catholic unity. Such belief is certainly opposed to Catholic teaching. There are, of course, those who are struggling with invincible ignorance about our most holy religion. Sincerely observing the natural law and its precepts inscribed by God on all hearts and ready to obey God, they live honest lives and are able to attain eternal life by the efficacious virtue of divine light and grace. Because God knows, searches and clearly understands the minds, hearts, thoughts, and nature of all, his supreme kindness and clemency do not permit anyone at all who is not guilty of deliberate sin to suffer eternal punishments.”
Pius IX clearly says that all those who are invincibly ignorant, and yet live upright lives ready to obey God, will be saved. God does not allow anyone who is not guilty of deliberate sin to suffer eternal punishment.
Some people are of the opinion that this text is only saying that God gives all such people the grace to convert to Catholicism before they die. The point that should be made about this, is that there is a clear contrast in the text between those who are “living in error and alienated from the true faith and Catholic unity,” and those who observe “the natural law and its precepts inscribed by God on all hearts and ready to obey God.” Thus, the statement made about the first group does not apply to the second. This is manifest even in the text, since Pius IX states that the first group cannot attain salvation whereas the second group can.
I would also note that the aforementioned position is forced to hold the position that these people who are “ observing the natural law and its precepts inscribed by God on all hearts and ready to obey God,” and live “honest lives,” nevertheless are unable to love God. This is a very strange position, since these people are ready to obey God.
From our next pope, Pius X, we have this same teaching clearly asserted in his Catechism. Cardinal Ratzinger made this comment about this Catechism: "The faith, as such, is always the same. Therefore, St. Pius X's catechism always retains its value . . . it should not be forgotten that that the Catechism stemmed from a text that was prepared by the Pope himself [Pius X] when he was bishop of Mantua. The text was the fruit of the personal catechetical experience of Giuseppe Sarto, whose characteristics were simplicity of exposition and depth of content."
Q: But if a man through no fault of his own is outside the Church, can he be saved? (A.9 Q.29)
A: If he is outside the Church through no fault of his, that is, if he is in good faith, and if he has received Baptism, or at least has the implicit desire of Baptism; and if, moreover, he sincerely seeks the truth and does God's will as best he can such a man is indeed separated from the body of the Church, but is united to the soul of the Church and consequently is on the way of salvation.
Now, what does he mean for a man to be united to the soul of the Church? He explains this in another article:
Q: In what does the Soul of the Church consist?(A.9 Q.22)
A: The Soul of the Church consists in her internal and spiritual endowments, that is, faith, hope, charity, the gifts of grace and of the Holy Ghost, together with all the heavenly treasures which are hers through the merits of our Redeemer, Jesus Christ, and of the Saints.
According to St. Pius X, then, someone who is outside the Church through no fault of his own, whether he belongs to some other sect of Christianity, or even if has only an implicit desire for baptism, can possess the grace of faith, hope, and charity, and thus be in the state of justification. This faith would have to be an implicit faith in Christ in the case of those who do not know of Him and His church.