"The Holy Father (Gregory XVI, Mirari Vos, Aug 15, 1832) censures in severe terms Indifferentism, or the pretense that one religion is as good as another, and that it makes no difference of what religion a man is, whether of any or none, providing he maintains a certain moral decorum. We need not dwell on this, for we have made many enemies by the earnestness with which we have insisted on the dogma that there is no salvation out of the Church. There are here and elsewhere many Catholics who are latitudinarian in their feelings, and are quite shocked to hear the doctrine of exclusive salvation asserted. They regard that doctrine as uncharitable, bigoted, intolerant, and altogether unsuitable to the liberal and enlightened age in which we live. We are, we think, in no danger of being included in their number, and we leave them to settle the matter with the doctrine of the Church so as to escape the Papal censure, the best way they can."
"Lamennais and Gregory XVI," Brownson's Quarterly Review, 1859 *I will post this up on my Brownson site today for those of you who want to sift through the entire article.