Mystici Corpus did not, of course, contain any solemn Magisterial declarations.
No, but Mystici Corporis did. Take a gander at Denzinger.
Well, I suggest that you take a look at your copy of Denzinger's. You will almost certainly find that the editor of that book was none other than Fr. Karl Rahner, the architect of the Second Vatican Council. And, yes, I misspelled (or, rather, my spell-checker, which does not know Latin) Mystici Corporis Christi. I could, of course, point out your typos, but being a Christian, I would regard that behavior as being uncharitable.
And your point is what? Denzinger is no good because Rahner was editor? Was he editor in 1943? Is this just an empty charge to CYA?
Go ahead with the typos, others have pointed them out...and I thanked them. :) You shouldn't be so sensitive about it.
So what was the purpose of the definition of membership contained in the encyclical Mystici Corporis?
During WII, the Catholic Church had one of the most extensive spy networks in the World. (The Church still does.) Pope Pius XII knew what was going on in nαzι Germany, and in 1943, he knew that the war was turning against them. Near the end of the war, the Church would establish the infamous "Rat Line," which would allow dozens of nαzι war criminals to escape Allied justice, and nooses.
Remember that Father Karl Rahner, after a few mild reprimands, was a theologian in good standing with the Church when Pius XII died. No doubt
Mystici Corporis Christi was influenced, not by Rahner, but by his predecessors in the German theological schools and Jesuit order.
The Church's theology in recent times, especially towards the Jews, was heavily influenced by the h0Ɩ0cαųst, Darwinian and atheistic materialism, Enlightenment philosophy, and higher Biblical criticism and historiography.