I thought it may be interesting for Roman Catholics to know where the word "Protestant" originates (from a well done article in Wikipedia):
"The word Protestant is derived from the Latin protestatio meaning declaration which refers to the letter of protestation by Lutheran princes against the decision of the Diet of Speyer in 1529, which reaffirmed the edict of the Diet of Worms against the Reformation.
Since that time, the term Protestantism has been used in many different senses, often as a general term to refer to Western Christianity that is not subject to Papal authority.
So.....whatever you may have heard, the ORIGINAL meaning of "Protestant" comes from those German princes who protested against an Emperor's laws against religious freedom.
As Americans, I would hope we could ALL be "protestant" in that sense....
Please note that while some may agree with all the doctrines defended in the Edict (which basically just condemns Luther and all his writings, along with all his followers--making provision for their arrest.) I trust no patriotic American would agree with Charles V's severe attempt to crush the Lutherans, along with religious freedom.
As stated above, this law is what they were protesting...