A Spanish friend of ours, who works at the World Bank, asked my friend Warren a question regarding religious observance in these United States.
He replied something to the effect that "you basically have the Christians, the Catholics, and the Jews". After he said something in this vein twice I piped up, being born and raised Catholic myself.
He said he stuck by this division and was not going to talk about it. That he didn't "know what the f--k" we Catholics are.
Catholicism represents the first Christian church, I protested. Henry the Eighth established the Church of England essentially so he could re-marry after divorcing--he did not invent Christianity by so doing. Neither did Mister Luther. I would not allow us Catholics to be eradicated by the "protest-ants", the "schismatics", the "break-offs" (and I didn't say the "splinter groups", but might have).
He stuck by his statement, and wouldn't discuss it.
For her purposes, as a non-American and presumably Catholic herself (Spain is over 90% Catholic), it's important to know two things. First, that when she sees statistics noting that 85% of Americans consider themselves to be "Christian", that certainly includes Catholics who are 25% or so of the total. Second, that many "Christians" in the U.S. do not in fact believe Catholics should be counted in their number, particularly, I've observed, those in the South.
This may be a definitional thing; as to what a "Christian" is in their minds. It may represent ignorance. But it also might be historical. In Europe everyone knows the Roman Catholic church first spread "Christianity", at least in the Western sphere. Martin Luther and Henry VIII came along later.
In the U.S., it was largely the Protestants who tamed the wild, at least in the Northeast. Columbus stayed pretty far south, below what we now know as the U.S.A., and he really didn't settle much square footage. The Catholic waves came much later--late 1800's for both the Irish and the Italians. The Poles and Germans factor in in big ways, too, but their waves are a little less distinct.
So, Warren, being from Massachusetts, home of the original landing of Puritans at the legendary Plymouth Rock, might very well see things this way.