Sandra, Catholics aren’t separate from Christians although the sense in which you use this terminology is one I hear from Protestants, often evangelical, who seek I suppose to want to separate themselves from what they preach and perceive as an illegitimate claim to be part of the ‘true” Church. Living in Latin American and in Latino majority populations in North America, I have noticed that this usage appears to be growing in popularity as the non-Catholic numbers increase, and it may also reflect Spanish usage or a tendency among Protestants who want to stress their differences with the Catholic majority who of course, historically until recently, have dominated.
Catholics are but one denomination within the Christian family, while those who’ve separated starting with Luther and the Anglicans-Episcopalians have branched out into, so I have heard in the United States, over twenty thousand different denominations. I raise this point, as our Pathfinder course is about learning the truth of ways we distinguish ourselves, in respect, for I am part of an ecumenical Franciscan community who takes vows, and whose members live in the world, and who therefore may be more attentive than many we worship among in our home congregations as to the manner in which phrases and words matter. I express my response in a spirit of peace.