Very true, and I don't think the author attempts to do so. In order to compare and contrast, he picks Protestant theologies that he thinks are typical, but I don't think he makes any presumption of uniformity regarding that. His goal is to explain the Catholic theology to those who might be more familiar with one or another Protestant theory.
Of course the same applies Roman Catholics...they leave Rome for other faiths all the time.
Such a price we pay for freedom of religion! Why couldn’t we have just been happy with the Inquistion!
I didn’t ask the author to speak for Protestants, I just asked him not to use “catholic” without a qualifier. He speaks for the Roman Church, no other body.
At this point in time at least, there is no human organization which is the exclusive “Catholic” church.
If there are any Christians at all outside the Roman Church (as your Magisterium has acknowledged for the last 50 years or so) than one cannot speak of the Roman Church as universal, or catholic.
What Catholic apologists must understand is that they must not address Protestant theology as if it were one monolithic body, but address each theological sticking point on its own. Catholicism it seems has one general theology, while Protestants may disagree on as much if not more with each other than with Catholic theology.
The main problem though that Catholics have with swaying Protestants, is that there is a good amount of evidence in the lack of capability that a human organization has to stay righteous. This is the core problem--not theological or liturgical differences. Being subject to a fallible human in Christianity rather than God is the core. And it's quite an uphill battle since the failings of Catholic leadership in history are so well known.