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.– But the Catholic faith is this, that we worship one God in the Trinity, and the Trinity in unity... Therefore let him who wishes to be saved, think thus concerning the Trinity. “But it is necessary for eternal salvation that he faithfully believe also in the incarnation of our Lord Jesus Christ...the Son of God is God and man...– This is the Catholic faith; unless each one believes this faithfully and firmly, he cannot be saved.”

From LaGrange's book Life Everlasting, under the chapter "The Number of The Elect" is the following:

..."Further, among non-Christians (Jєωs, Mohammedans, pagans) there are souls which are elect.  Jєωs and Mohammedans not only admit monotheism, but retain fragments of promitive revelation and of Mosaic revelation.  They believe in a God who is a supernatural rewarder, and can thus, with the aid of grace, make an act of contrition.  And even for pagans, who live in invincible, involuntary ignorance of the true religion, and who still attempt to observe the natural law, supernatural aids are offered, by means known to God.  These, as Pius IX says, can arrive at salvation.  God never commands the impossible.  To him who does what is in his power God does not refuse grace."