Calvin on the Church

It hence follows, that they egregiously mistake who form an opinion of the Church according to their own perceptions. And surely if that celebrated Prophet, who was endued with so enlightened a mind, was so deceived, when he attempted by his own judgment to form an estimate of God’s people, what shall be the case with us, whose highest perspicuity, when compared with his, is mere dullness? Let us not then determine any thing rashly on this point; but rather let this truth remain fixed in our hearts — that the Church, though it may not appear to our eyes, is sustained by the secret providence of God. Let it also be remembered by us, that they are foolish and presumptuous who calculate the number of the elect according to the extent of their own perception: for God has a way, easy to himself, hidden from us, by which he wonderfully preserves his elect, even when all things seem to us past all remedy...

Since then the grace of God prevails so much in an extreme state of things, let us not lightly give over to the devil all those whose piety does not openly appear to us. It also ought to be fully imprinted on our minds, — that however impiety may everywhere prevail, and dreadful confusion spread on every side, yet the salvation of many remains secured under the seal of God. f338 But that no one may under this error indulge his own sloth, as many seek hiding-places for their vices in the hidden providences of God, it is right to observe again, — that they only are said to be saved who continue sound and unpolluted in the faith of God. This circumstance in the case ought also to be noticed, — that those only remained safe who did not prostitute their body, no, not even by an external act of dissimulation, to the worship of idols; for he not only ascribes to them a purity of mind, but that they had also kept their body from being polluted by any filthiness of superstition.- John Calvin, commenting on Romans 11:2