Encyclical Letters of Bl. Pope Pius IX, Singulari Quidem (1856)
“Outside of the Church, nobody can hope for life or salvation unless he is excused through ignorance beyond his control.”
Encyclical Letters of Bl. Pope Pius IX Quanto Conficiamur Moerore (1863) “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.”
The Explanation of the Baltimore Catechism (1891)
“If, then, we found a Protestant who never committed a mortal sin after Baptism, and who never had the slightest doubt about the truth of his religion, that person would be saved; because, being baptized, he is a member of the Church, and being free from mortal sin he is a friend of God and could not in justice be condemned to Hell.”
The Catechism of St. Pope Pius X (1910)
“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.”
The Catholic Encyclopedia (1913)
“The Catholic Church has ever taught that nothing else is needed to obtain justification than an act of perfect charity and of contrition. Whoever, under the impulse of actual grace, elicits these acts receives immediately the gift of sanctifying grace, and is numbered among the children of God. Should he die in these dispositions, he will assuredly attain heaven.”
The Spirit of Catholicism (1935)
“Therefore the Church is the true and ordinary institute of the grace and truth of Jesus. But that does not prevent there being, alongside this ordinary institute, extraordinary ways of salvation, or hinder the grace of Christ from visiting particular men without the mediation of the Church. But because and in so far as the Body of Christ comprehends all those who are saved by Christ, those also who are visited by His grace in this immediate way belong to His Church.”
Radio Replies (1938, 1940, 1942)
“Good non-Catholics who, through no fault of their own, have never known the Catholic Church to be the true Church, and who die sincerely repentant of such sins as they have committed, will save their souls.”
Official Letter Authorized by Pope Pius XII
Letter to the Archbishop of Boston
from the Congregation for the Doctrine of the Faith
Concerning the Salvation of Non-Catholics
8 August 1949
from F. Cardinal Marchetti-Selvaggiani
to Most Reverend Richard James Cushing
“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. However, this desire need not always be explicit…”
For the entire letter in context,
catholicity.elcore.net/SalvationOfNonCatholicsInLetterToBoston.html