First, of all as a Lutheran, I am not a "Protestant", and I have never called myself that. I will happily go by Catholic, Orthodox, Evangelical. Anyways, our understanding is very much not like Zwingli's. So, yes, Marburg is definitely the place to see the spirits dividing.
With that clarified, let's see what the writer of the article comes down to at the end.
For some reason, we always come to Flannery O'Connor. It does baffle me a bit. She is said to be indebted to Jesuit scholar William F. Lynch, of whom I have not heard. My guess is that he is an American.
From the internet:
An outstanding article
7 hours ago