Quotes which show John Calvin stating the early Church (the Catholic Church) was once the true Church of Christ:"But let us forgive them this, and let them take for granted that primacy was divinely bestowed on the Romish see, and has been sanctioned by the uniform consent of the ancient church; still there is room for this primacy only on the supposition that Rome has both a true church and a true bishop" John Calvin - The Necessity of Reforming the Church (1543)
Keep in mind with this statement from CAF, "the Catholic Church" means= Romanism. This snippet quote appears to be taken from a web page like this.
Calvin's statement is actually part of a complex argument. From this statement quoted at CAF, it appears that Calvin is granting the Roman church "primacy...sanctioned by the uniform consent of the ancient church," and that "Rome has both a true church and a true bishop." Well, if he did grant all this, this statement in context certainly doesn't prove it:
But, because they hold that the communion of the Church is confined to a kind of regimen which they have struck out for themselves, they think it sufficient to decide the victory in their favor, when they point to our alienation from the Romish See. But to this vaunted primacy of the Romish See it is not difficult to reply. It is a subject, however, on which I will not here enter, both because it would occupy too much time, and because it has been amply discussed by our writers. I will only beg your Imperial Majesty, and Most Illustrious Princes, to listen to Cyprian, when he points out a better method of ascertaining the true communion of the Church, than that of referring it, as our opponents do, to the Roman Pontiff alone. For, after placing the only source of ecclesiastical concord in the episcopal authority of Christ, which episcopal authority he affirms that each bishop, to the extent to which it has been communicated, holds entire, he thus proceeds: “There is one church, which, by the increase of its fruitfulness, spreads into a multitude, just as there are many rays of the sun, but only one light, many branches in a tree, but one trunk, upheld by its tenacious root; and when many streams flow from one fountain, though, from the copiousness of the supply, there seems a division into parts, still, in regard to the origin, unity is preserved. Separate a ray from the body of the sun, the unity of the light is not divided. Break a branch from a tree, that which is broken cannot germinate. Cut off a stream from the fountain, and it dries up. So, also, the Church of God, irradiated with light, sends its beams over the whole world. Still it is one light which is everywhere diffused. The unity of the body is not violated.” (Cyprian De Unitat. Ecclesiae.) Heresies and Schisms, therefore, arise when a return is not made to the origin of truth, when neither the head is regarded, nor the doctrine of the heavenly Master preserved. Let them then show us a hierarchy in which the bishops are distinguished, but not for refusing to be subject to Christ, in which they depend upon him as the only head, and act solely with reference to him, in which they cultivate brotherly fellowship with each other, bound together by no other tie than his truth; then, indeed, I will confess that there is no anathema too strong for those who do not regard them with reverence, and yield them the fullest obedience. But is there any thing like this in that false mask of hierarchy on which they plume themselves? The Roman Pontiff alone as Christ’s vicar is in the ascendant, and domineers without law and without measure,after the manner of a tyrant, nay, with more abandoned effrontery than any tyrant. The rest of the body is framed more according to his standard than that of Christ. The light of which Cyprian speaks is extinguished, the copious fountain cut off; in short, the only thing exhibited is the tallness of the tree, but a tree dissevered from its root.
I am aware that our adversaries have good reason for laboring so strenuously to maintain the primacy of the Romish See. They feel that on it both themselves and their all depend. But your part, Most Invincible Emperor, and Most Illustrious Princes, is to be on your guard in order that they may not with vain glosses deceive you, as they are wont to deceive the unwary. And, first, this vaunted supremacy, even themselves are forced to confess, was established by no divine authority, but by the mere will of man. At least, when we give proof of this fact, though they do not expressly assent, they seem as if ashamed to maintain the opposite. There was a time, indeed, when they audaciously perverted certain passages of Scripture to confirm this palpable falsehood, but as soon as we came to close quarters, it was found easy to pluck out of their hands the bits of lath, to which, when at a distance, they had given the appearance of swords. Abandoned, accordingly, by the Word of God, they flee for aid to antiquity. But here, also, without much ado, we dislodge them. For both the writings of holy Fathers, the acts of Councils, and all history, make it plain that this height of power, which the Roman Pontiff has now possessed for about four hundred years, was attained gradually, or rather was either craftily crept into, or violently seized. But let us forgive them this, and let them take for granted that primacy was divinely bestowed on the Romish See, and has been sanctioned by the uniform consent of the ancient Church; still there is room for this primacy only on the supposition that Rome has both a true church and a true bishop. For the honor of the seat cannot remain after the seat itself has ceased to exist. I ask, then, in what respect the Roman Pontiff performs the duty of a bishop, so as to oblige us to recognize him as a bishop? There is a celebrated saying of Augustine, “Bishopric is the name of an office, and not a mere title of honor.” And ancient Synods define the duties of a bishop to consist in feeding the people by the preaching the Word, in administering, the sacraments, in curbing clergy and people by holy discipline, and, in order not to be distracted from these duties, in withdrawing from all the ordinary cares of the present life. In all these duties, presbyters ought to be the bishop’s coadjutors. Which of them do the Pope and his Cardinals pretend to perform? Let them say, then, on what ground they claim to be regarded as legitimate pastors, while they do not, with their little finger, in appearance even, touch any part of the duty.
But let us grant all these things, viz., that he is a bishop who entirely neglects every part of his duty, and that a Church which is destitute, as well of the ministry of the Word as of the pure administration of the Sacraments; still, what answer is made when we add not only that these are wanting, but that every thing which exists is directly the reverse? For several centuries that See has been possessed by impious superstitions, open idolatry, perverse doctrines, while those great truths, in which the Christian religion chiefly consists, have been suppressed. By the prostitution of the Sacraments to filthy lucre, and other abominations, Christ has been held up to such extreme derision, that he has in a manner been crucified afresh. Can she be the mother of all churches, who not only does not retain, I do not say the face, but even a single lineament, of the true Church, and has snapt asunder all those bonds of holy communion by which believers should be linked together? The Roman Pontiff is now opposing himself to the reviving doctrines of the gospel, just as if his head were at stake. Does he not, by this very fact, demonstrate that there will be no safety for his See unless he can put to flight the kingdom of Christ? Your Imperial Majesty is aware how wide a field of discussion here opens upon me. But to conclude this point in a few words: I deny that See to be Apostolical, wherein nought is seen but a shocking apostacy — I deny him to be the vicar of Christ, who, in furiously persecuting the gospel demonstrates by his conduct that he is Antichrist — I deny him to be the successor of Peter, who is doing his utmost to demolish every edifice that Peter built — and I deny him to be the head of the Church, who by his tyranny lacerates and dismembers the Church, after dissevering her from Christ, her true and only Head. Let these denials be answered by those who are so bent on chaining the hierarchy of the Church to the Romish See, that they hesitate not to subordinate the sure and tried doctrines of the gospel to the authority of the Pope. Yea, I say, let them answer; only do you, Most Invincible Emperor, and Most Illustrious Princes, consider whether, in so calling upon them, the thing I ask is just or unjust.