Against the Heresies, by Archbishop Marcel Lefebvre, Page 216: “Evidently, certain distinctions must be made.  Souls can be saved in a religion other than the Catholic religion, but not by this religion.  There may be souls who, not knowing Our Lord, have by the grace of the good Lord, good interior dispositions, who submit to God...But some of these persons make an act of love which implicitly is equivalent to baptism of desire.  It is uniquely by this means that they are able to be saved.”
 
Against the Heresies, by Archbishop Marcel Lefebvre, Page 217: “One cannot say, then, that no one is saved in these religions…”
 
Against the Heresies, by Archbishop Marcel Lefebvre, Pages 217-218: “This is then what Pius IX said and what he condemned.  It is necessary to understand the formulation that was so often employed by the Fathers of the Church:  ‘Outside the Church there is no salvation.’  When we say that, it is incorrectly believed that we think that all the Protestants, all the Moslems, all the Buddhists, all those who do not publicly belong to the Catholic Church go to hell.  Now, I repeat, it is possible for someone to be saved in these religions, but they are saved by the Church, and so the formulation is true: Extra Ecclesiam Nulla Salus.  This must be preached.”

Pope Gregory XVI, Summo Iugiter Studio (# 2), May 27, 1832:
“Finally some of these misguided people attempt to persuade themselves and others that men are not saved only in the Catholic religion, but that even heretics may attain eternal life.”

Pope Pius IX, Qui Pluribus (# 15), Nov. 9, 1846:
"Also perverse is that shocking theory that it makes no difference to which religion one belongs, a theory greatly at variance even with reason. By means of this theory, those crafty men remove all distinction between virtue and vice, truth and error, honorable and vile action. They pretend that men can gain eternal salvation by the practice of any religion, as if there could ever be any sharing between justice and iniquity, any collaboration between light and darkness, or any agreement between Christ and Belial."

Pope Innocent III, Fourth Lateran Council, Constitution 1, 1215, ex cathedra: “There is indeed one universal Church of the faithful, outside of which nobody at all is saved, in which Jesus Christ is both priest and sacrifice.”

Pope Eugene IV, Council of Florence, Sess. 8, Nov. 22, 1439, ex cathedra:
“Whoever wishes to be saved, needs above all to hold the Catholic faith; unless each one preserves this whole and inviolate, he will without a doubt perish in eternity.”