CCC 846-848, start at 830 for more context
“Here is how the Catechism of the Catholic Church begins to address this topic: “How are we to understand this affirmation, “Outside the Church there is no salvation”, often repeated by the Church Fathers? Reformulated positively, it means that all salvation comes from Christ the Head through the Church which is his Body” (CCC 846).” https://www.catholic.com/magazine/print-edition/what-no-salvation-outside-the-church-means
“that all salvation comes from Christ the Head” … we get from Jesus’ own words recorded by John: “I am the way, and the truth, and the life; no one comes to the Father, but by me” (Jn 14:6) https://www.catholic.com/magazine/print-edition/what-no-salvation-outside-the-church-means
But this isn’t ALL that needs to be said about how we can all get to Heaven. The Catholic Church has historically recognized the importance of explaining further THE MEANS through which salvation is offered through Christ, because Jesus also spoke of this:
- He who believes and is baptized will be saved. (Mk 16:16)
- [U]nless you repent you will all likewise perish. (Lk 13:3)
- [H]e who eats my flesh and drinks my blood has eternal life, and I will raise him up at the last day. (Jn 6:54)
Jesus associated salvation with baptism, confession, and the Eucharist, and so they are administered through the Church, the last two needing a validly ordained priest for their administration.
“through the Church which is his Body” … “Since the sacraments are the ordinary means through which Christ offers the grace necessary for salvation, and the Catholic Church that Christ established is the ordinary minister of those sacraments, it is appropriate to state that salvation comes through the Church.” https://www.catholic.com/magazine/print-edition/what-no-salvation-outside-the-church-means
“Since Jesus established the Catholic Church as necessary for salvation, those who knowingly and willingly reject him or his Church cannot be saved. We see this in Jesus’ teaching: “He who is not with me is against me, and he who does not gather with me scatters” (Mt 12:30). Also: “[I]f he [a sinning brother] refuses to listen even to the church, let him be to you as a Gentile and a tax collector” (Mt 18:17). Paul warned similarly: “As for a man who is factious, after admonishing him once or twice, have nothing more to do with him, knowing that such a person is perverted and sinful; he is self-condemned” (Ti 3:10-11). https://www.catholic.com/magazine/print-edition/what-no-salvation-outside-the-church-means
Having said all this, we must recognize that this doctrine is not as far reaching as some imagine it to be. People will sometimes ask, “Does this means non-Catholics are going to hell?” Not necessarily.” https://www.catholic.com/magazine/print-edition/what-no-salvation-outside-the-church-means
“The Church recognizes that God does not condemn those who are innocently ignorant of the truth about his offer of salvation. Regarding the doctrine in question, the Catechism of the Catholic Church (quoting Vatican II document Lumen Gentium, 16) states:
This affirmation is not aimed at those who, through no fault of their own, do not know Christ and his Church: Those who, through no fault of their own, do not know the Gospel of Christ or his Church, but who nevertheless seek God with a sincere heart, and, moved by grace, try in their actions to do his will as they know it through the dictates of their conscience—those too may achieve eternal salvation. (CCC 847)”
“Vatican II document Gaudium Et Spesteaches similarly on the possibility of salvation:
All this holds true not only for Christians, but for all men of good will in whose hearts grace works in an unseen way. For, since Christ died for all men, and since the ultimate vocation of man is in fact one, and divine, we ought to believe that the Holy Spirit in a manner known only to God offers to every man the possibility of being associated with this paschal mystery. (22)”
“If I had not come and spoken to them, they would not have sin; but now they have no excuse for their sin” (John 15:22; see also John 9:41). Jesus presents a very important principle here. A person is not responsible for what they could not have known. The implication is it is possible to have a salvific link with Christ without knowing him formally. If this is so, and it is, according to Scripture, then it stands to reason that in the same way, one can have a salvific relationship with the Church without knowing the truth that the Church is the fullness of Christ on this earth (see also the case of Cornelius the centurion in Acts 10:1-4, 34-35).” https://www.catholic.com/magazine/online-edition/is-there-really-no-salvation-outside-the-catholic-church
“What I mean by a “formal relationship” with the Church is that a person has been formally baptized into Christ and has made a profession of faith in the one, true faith of the Catholic Church (assuming he has reached the age of accountability). However, a person can possibly have a salvific link with Christ and his Church in various ways some of which are known to God alone. This can be via the valid sacraments they may have, e.g., all seven with the Orthodox, or two with Protestants (baptism and matrimony). Or, it may be via what the Council fathers called “the images and shadows” of truth that the various world religions possess. Indeed, even “those who, without blame on their part, have not yet arrived at an explicit knowledge of God and with His grace strive to lead a good life” will not be denied by Divine Providence what the Council fathers called “the helps necessary for salvation” (Lumen Gentium,16).” https://www.catholic.com/magazine/online-edition/is-there-really-no-salvation-outside-the-catholic-church
“We must remember that we are not the judges of salvation. God is the sole and final judge. We do not know who is truly “invincibly ignorant” and who is not. Therefore, we must be careful to “evangelize all men” as the Catechism commands us and leave the judging to God.” https://www.catholic.com/magazine/online-edition/is-there-really-no-salvation-outside-the-catholic-church
“And if one has rejected the truth, then there is no way he can merit heaven apart from repentance and the acceptance of the truth. The Church makes very clear: “The words bind and loose mean: whomever you exclude from your communion, will be excluded from communion with God; whomever you receive anew into your communion, God will welcome back into his. Reconciliation with the Church is inseparable from reconciliation with God” (CCC 1445).” https://www.catholic.com/magazine/online-edition/is-there-really-no-salvation-outside-the-catholic-church
TLDR “As we have seen, God introduced salvation to the world through his chosen people, the Jews. God’s revelation to the Jews found its fulfillment in Christ, the Messiah, who established the Catholic Church. The grace necessary for salvation continues to come from Christ, through his Church. Those who innocently do not know and embrace this might still attain salvation but those who knowingly and willingly choose to reject it, reject salvation on God’s terms.” https://www.catholic.com/magazine/online-edition/is-there-really-no-salvation-outside-the-catholic-church
- There is no salvation apart from Christ and his One, Holy, Catholic, and Apostolic Church. This is an infallible teaching and not up for debate among Catholics.
- Those who are “invincibly” ignorant concerning the truth of #1 above will not be culpable for this lack of knowledge before God.
- Those in the category of #2 have the real possibility of salvation even if they never come to an explicit knowledge of Christ and/or his Church. https://www.catholic.com/magazine/online-edition/is-there-really-no-salvation-outside-the-catholic-church
“The bottom line is: the straight and narrow road that leads to heaven is not an easy road to begin with, even for those gifted with the fullness of truth found in the Catholic Church alone (see Matt. 7:13; I Peter 4:18). But without the Church and sacraments Christ has provided as the ordinary means for our sanctification, it is even more difficult.” https://www.catholic.com/magazine/online-edition/is-there-really-no-salvation-outside-the-catholic-church