Many people tend to believe that the word "Catholicism" is a denomination that serves to differentiate it, in the field of Christianity, from other branches such as "Protestantism" or "Orthodoxy". It is known, for example, that Catholics pray the rosary, venerate the Pope, go to mass on Sundays, and that their priests are celibate.
These features, among others, are supposed to distinguish Catholicism from Protestantism.
Catholics are also said to have a particular ethnic origin: the Irish are Catholic while the Scots are Presbyterian;
(1)the Italians are Catholic (2) the Norwegians are Lutheran.
In certain places, Catholics are associated with a certain social class.
A century ago in the United States, Catholics were almost exclusively working class and Protestants made up the business class. The same thing happened in England until very recently.
Although these and other stereotypes are part of popular culture, they are still stereotypes. These are differences that tend to separate people united by their religious upbringing: to be Irish is to be Catholic.
This tendency to understand religious confession as a sociological category is not unique to Catholicism, it is shared by most religious traditions. Belonging to one religion or another depends a lot on where you live and how you perceive yourself within the culture as a whole.