Charles Hodge ((1797–1878) wrote a letter on behalf of the PCUSA in politely but frankly declining to send representatives to attend Vatican I (1869–70). Scott Clark says of the letter,
This is an eloquent summary of the same Protestant case against Romanism… Confessional Protestants are the true catholics (my emphasis), i.e., we still believe the holy catholic faith revealed in God’s Word and confessed by the church in all times and places. What we reject is not the catholic faith but Romanism (Clark’s emphasis). Those two things must not be confused.
Here’s a quote from Hodge’s letter (from the Heidelblog):
We are not heretics… We receive all those doctrines concerning sin, grace and predestination, known as Augustinian, which doctrines received the sanction not only of the Council of Carthage and of other provincial Synods, but of the Ecumenical Council of Ephesus AD431, and of Zosimus, bishop of Rome.
We therefore cannot be pronounced heretics without involving in the same condemnation the whole ancient church.
Neither are we schismatics. We cordially recognize as members of Christ’s visible Church on earth, all those who profess the true religion together with their children. We are not only willing but earnest to hold Christian communion with them, provided they do not require, as conditions of such communion, that we profess doctrines which the Word of God condemns, or that we should do what the Word forbids. If in any case any Church prescribes such unscriptural terms of fellowship, the error and the fault is with that church and not with us.
The tenor of this letter is similar to Guido de Brès’ letter to King Philip II when he presented the Belgic Confession of Faith to the king in 1561. As he wrote in the Confession, he denied that the Protestants were rebels or heretics:
[we] detest the Anabaptists and other seditious people, and in general all those who reject the higher powers and magistrates and would subvert justice, introduce community of goods, and confound that decency and good order which God has established among men (BC Article 36).
A portion of his letter to the king reads:
However, since we had the fear of God before our eyes and thus dreading the threat of Jesus Christ, who says that He will deny us before God His Father, should we deny Him before men: we offer our backs to the whip’s lash, our tongues to the knives, the mouth to the muzzle, and the whole body to the flames. For we know that whoever will follow Christ must take up his cross and deny himself.
… These believers, while offering and abandoning their bodies and their goods to the King, humbly supplicate his Majesty that it may be granted them to render obedience to God in what He requires. For we have not the right nor may we refuse to obey Him, because He hath made us and purchased us for Himself through the payment of the most dear price of infinite worth.
Five years later, Guido de Brès willingly offered his neck to the Roman Catholic scaffold as a martyr for the One, Holy, Catholic and Apostolic Church.