Nihilominus tamen verum est quod sacramentum Baptismi prodest parvulis merito fidei Ecclesiae militantis, quae, quamvis possit deficere in aliquibus personis specialiter, generaliter tamen nunquam deficit nec deficiet, iuxta illus Matthaei ultimo, 20, "Ecce ego vobiscum sum usque ad consummationem saeculi." Unde sicut species semper salvatur in aliquo individuorum, sic fides in aliquo fidelium, et hoc, divina providentia faciente. Nec unquam fuit, postquam incepit Ecclesia, quin semper esset aliquid qui Deo placeret; sic nec unquam erit.
"Nevertheless it is true that in the sacrament of Baptism the merit of the faith of the Church Militant profits the children [i.e. the ones baptised], which [faith], although it can fail in some persons specially [as individuals], nevertheless never generally fails nor will fail, as that statement in the last chapter of Matthew says, verse 20, "Behold I am with you even until the consummation of the age." Whence just as the species in always preserved in any one of [its] individuals, so is the faith [preserved] in any one of the faithful, and this by the working of divine providence. Nor ever, since the Church began, has there failed to be someone who pleased God, as also there never will be."
--St Bonaventure, IV Sent., dist. 4 pars 1 dub.2.
Protestants love the idea of a remnant Church holding out against the tide of the unfaithful. Of course they also like to imagine that they themselves are the remnant Church, and that the remnant of the faithful across the ages were just like them, rather than being faithful Catholics. They certainly do not like the idea of the merits of the faithful remnant helping to remit the sins of others, nor of their faith serving for infants in making their baptism valid, if their parents are faithless. All in all an interesting passage.
