[GCC Catholic]

That would be making it an ad hom. There is no such implication with Romanist or Roman Catholic.

"Romanist" is an offensive term: Definition by Webster

"Roman Catholic" has origins as an offensive term, but generally is no longer considered one. To use it to describe the entire Catholic Church is usually understood, but is inaccurate.

Dr. Eckleburg's suggestion allows all three branches of Christianity a universal conception.

If we're speaking about the "three branches of Christianity" (and we are, as all three groups profess Trinitarian Christianity), then Dr. Eckleburg needs a new term for the group that the average American would consider "Protestant Christians".

[the_conscience]

"Romanist" is an offensive term: Definition by Webster

It's descriptive of the Church of Rome and any offense is merely on the part of the person who believes it's offensive.

If we're speaking about the "three branches of Christianity" (and we are, as all three groups profess Trinitarian Christianity), then Dr. Eckleburg needs a new term for the group that the average American would consider "Protestant Christians".

Protestant Christians believe themselves to be Catholic so then Romanists and Orthodox need a new term.