most of us “cradle Catholics” here, those of us who were not brought up in another Christian denomination, really are unsure about those labels as well. For myself, if I refer to a “Protestant” teaching or body I am referring to one of the leaders of the Protestant Reformation, a historical event or process that happened in the 16th century, and the doctrines those Reformers-Luther, Calvin, Zwingli etc. and their successors taught, and the denominations that today trace their origins with those leaders.
Protestant as used today is a very inexact term used by many Catholics to refer to Christians who are not Catholic or Orthodox. Many members of denominations that trace their roots to the Reformation do not know the history of the beliefs of their founder or their congregation, and no longer consider the doctrinal, organizational and disciplinary issues that people suffered and died for years ago to be important.
If I use the word “fundamentalist” I should be referring to those groups, leaders, writers or teachers that adhere to and insist upon the validity of the 6 fundamentals defined early in the last century by those denominations. I should only use that term about those who self-select, and identify themselves as adherents to those fundamentals, to the exclusion of all other Christian creeds or structures.
Evangelical is also a self-selected term and I should properly use that term toward those who describe themselves as “Bible Christians” whose only rule of belief and practice is the Scripture, and particularly those who feel called to evangelize unchurched people with the Gospel message. The Evangelical movement or reform is a historical movement within the original Protestant denominations based on the need to return to reliance on Sacred Scripture, and to get away from some abuses that were perceived in those denominations, and the need for missionary activity in non-European lands. Unfortunately it is hard to be accurate in using that term, as some self-identified evangelicals expend their efforts on trying to convert those who have already accepted the Gospel, yet belong to different denominations, especially Catholics, especially Hispanic Catholics.
As there are literally hundreds of non-Catholic Christian denominations, some with similar sounding names, Catholics should be forgiven if they misidentify any these branches and their adherents.
In a nutshell, we try to rely on using words or labels that the persons and denominations we are debating use to identify themselves.