"The twofold error of despising the true, and submitting to a false Church" By John Calvin (ICR IV. 1-10,11)

Section 10. We must on no account forsake the Church distinguished by such marks. Those who act otherwise are apostates, deserters of the truth and of the household of God, deniers of God and Christ, violators of the mystical marriage.

We have said that the symbols by which the Church is discerned are the preaching of the word and the observance of the sacraments, for these cannot any where exist without producing fruit and prospering by the blessing of God. I say not that wherever the word is preached fruit immediately appears; but that in every place where it is received, and has a fixed abode, it uniformly displays its efficacy. Be this as it may, when the preaching of the gospel is reverently heard, and the sacraments are not neglected, there for the time the face of the Church appears without deception or ambiguity; and no man may with impunity spurn her authority, or reject her admonitions, or resist her counsels, or make sport of her censures, far less revolt from her, and violate her unity, (see2.1.10, and 4.3.12).

 For such is the value which the Lord sets on the communion of his Church, that all who contumaciously alienate themselves from any Christian society, in which the true ministry of his word and sacraments is maintained, he regards as deserters of religion. So highly does he recommend her authority, that when it is violated he considers that his own authority is impaired. For there is no small weight in the designation given to her, "the house of God," "the pillar and ground of the truth," (1Ti 3: 15). By these words Paul intimates, that to prevent the truth from perishing in the world, the Church is its faithful guardian, because God has been pleased to preserve the pure preaching of his word by her instrumentality, and to exhibit himself to us as a parent while he feeds us with spiritual nourishment, and provides whatever is conducive to our salvation. Moreover, no mean praise is conferred on the Church when she is said to have been chosen and set apart by Christ as his spouse, "not having spot or wrinkle, or any such thing," (Eph 5: 27), as "his body, the fulness of him that fillets all in all," (Eph 1: 23). Whence it follows, that revolt from the Church is denial of God and Christ. Wherefore there is the more necessity to beware of a dissent so iniquitous; for seeing by it we aim as far as in us lies at the destruction of God's truth, we deserve to be crushed by the full thunder of his anger. No crime can be imagined more atrocious than that of sacrilegiously and perfidiously violating the sacred marriage which the only begotten Son of God has condescended to contract with us.

Section 11. These marks to be the more carefully observed, because Satan strives to efface them, or to make us revolt from the Church. The twofold error of despising the true, and submitting to a false Church.

Wherefore let these marks be carefully impressed upon our minds, and let us estimate them as in the sight of the Lord. There is nothing on which Satan is more intent than to destroy and efface one or both of them - at one time to delete and abolish these marks, and thereby destroy the true and genuine distinction of the Church; at another, to bring them into contempt, and so hurry us into open revolt from the Church. To his wiles it was owing that for several ages the pure preaching of the word disappeared, and now, with the same dishonest aim, he labours to overthrow the ministry, which, however, Christ has so ordered in his Church, that if it is removed the whole edifice must fall. How perilous, then, nay, how fatal the temptation, when we even entertain a thought of separating ourselves from that assembly in which are beheld the signs and badges which the Lord has deemed sufficient to characterise his Church! We see how great caution should be employed in both respects. That we may not be imposed upon by the name of Church, every congregation which claims the name must be brought to that test as to a Lydian stone. If it holds the order instituted by the Lord in word and sacraments there will be no deception; we may safely pay it the honour due to a church: on the other hand, if it exhibit itself without word and sacraments we must in this case be no less careful to avoid the imposture than we were to shun pride and presumption in the other.

From "The Institutes of the Christian Religion" Book IV Chapter 1, 10,11  Henry Beveridge Translation