By “old” I mean men who lived before the 20th century, especially those who were part of the Protestant Reformation (c. 16th-17th centuries) and their more immediate heirs. I use the term “Protestant” in its theological and historical sense, where it denotes a member or follower of any of the Western Christian churches that are separate from the RCC and follow the principles of the Reformation, including the Baptist, Presbyterian, and Lutheran churches. . . . Protestants are so called after the declaration (protestatio) of Martin Luther and his supporters dissenting from the decision of the Diet of Spires (1529), which reaffirmed the edict of the Diet of Worms against the Reformation. All Protestants reject the authority of the Papacy, both religious and political, and find authority in the text of the Bible.
Discovering the views of old Protestants on the Pope is not hard because they practically spoke with one voice and judgment. Their strong unity is evident from the fact that their interpretation on this made its way into their most important consensus documents, namely, their confessions of faith. Plainly they believed to know God’s mind on the matter because they appealed to Scripture for justification of their conclusions.