(...)Athough we ought always to hope, for the sake of charity, that this or that Protestant is in good faith, we can’t be sure that he is in good faith, nor, for that matter, can he. Therefore we should always encourage the conversion of a Protestant, if only for safety’s sake. But, you know, even if you could be certain that some friend of yours was in good faith, and was on the whole a clean-living sort of person, so that there was no great reason to worry about him, it isn’t true to say that you and he enjoy exactly the same supernatural advantages. First, you have the certainty of faith; you are spared the anxious uncertainties which often assail him; he’s not certain whether there is a future life, whether his life’s worth living, whether anything you do or say really matters much – from these doubts you are set free. Second, you have access, where he has no access, to sacramental grace; he can win forgiveness for his sins (for example) only by an act of perfect contrition, and who can be certain that he is making an act of perfect contrition? Whereas for you attrition suffices, as long as you make use of the sacrament of penance. Third, you have the merits of the Church at your disposal; you can go out to Rome in the vacation and get a plenary indulgence, or (if your dispositions are not sufficient for that) an indulgence of some kind; he can go out to Kamchatka and he won’t get off a day’s Purgatory for it. The reason why you don’t realize your privileges as Catholics is because you don’t use them more.
--Msgr. Ronald Knox,
The Unconscious Catholic
