The largest denomination in the Netherlands is in fact Catholicism. The secularization just hit the protestants churches harder than the catholic church.
I used to be an altar boy here (access to every part of the church, including the "secret" chappel in the Bethaniensteeg. Secret passages galore, I can tell you
That looks plan spectacular! How old is that cathedral! Structures like that are often several hundred years old! I like much of today's architecture also, but it has nothing on this!