I haven't read the whole thing, but I think Father Most is wrong here, early on in the first work cited:
On August 15, 1883, Pope Gregory XVI, in his Mirari Vos told us that there is "a most fruitful cause of the evils with which, we lament, the Church is now afflicted, that is, indifferentism."5 He explains what he means by indifferentism, namely, "that evil opinion that souls can attain eternal salvation by just any profession of faith, if their morals follow the right norm" and "from this most foul font of indifferentism flows that absurd view, or rather madness, that one should defend and vindicate for just anyone freedom of conscience."
In the first quotation, the Pope says that not just any profession of faith has the power to save a man, that is, one cannot be saved by just any sort of faith. But: Can a person be saved in spite of errors in faith, if he is in good faith? Pius IX, who also spoke most forcefully against indifferentism says yes: "God ... because of His supreme goodness and clemency, by no means allows anyone to be punished with eternal punishment who does not have the guilt of voluntary fault."6 Pius IX of course knew that there are two groups of requirements for salvation: a certain minimum faith that God exists, and rewards justly, plus keeping the moral law as one knows it. He tells us, then, that if this second requirement is met, somehow the first will be provided for also. He tells us the fact, without explaining the how.
If Fr. Most is saying, for example, that Pius IX's statement would support the claim that a Jew, Muslim, etc. who is aware of the claim of Christians that Christ is the Son of God and denies the divinity of Christ can be saved despite that error if it is in "good faith," he's wrong. And that's just an example.
Let's follow Fr. Most's own procedure - reconciling two incontrovertible truths. The Athanasian Creed tells us that no one can be saved without the Catholic faith, and then sets forth the minimum of what the faith must contain, which includes faith in the divinity of Christ, both God and man. When one reads Pius IX's statement that God will not allow someone who lacks "voluntary fault" to suffer everlasting punishment, one can conclude only one of two things with regard to the Jew or Muslim who denies Christ: that denial is the product of some fault on their part (eliminating their "good faith"), or God will not let them die in that error if they in fact have "good faith," and they will then be illumined by the Holy Ghost before death to accept Our Savior as both God and man.
So there can be no "good faith" that saves in "spite of errors" when it comes to the things that must be believed to have the necessary Catholic faith
- WHICH IS "THE CERTAIN MINIMUM FAITH IN GOD" WHICH IS REQUIRED.
Maybe Fr. Most was not implying otherwise, but I doubt it. Because then it seems he would have explained the apparent inconsistency between Gregory XVI and Pius IX in the way I did above.