Thing is that very few Protestants ever even tried to remain ‘unified’ in the way that RCs define the term.
Most Protestants will not condemn all others to eternal damnation like Roman Catholicism condemns all non-Catholic Christians too.
Actually quite a few of the fr non Catholics here do exactly that, damning everyone else
The second half of your sentence is false. (See, for example, the response of the Holy Office in the Father Feeney case in 1948.) I have no idea what that does to the first half of your sentence.
I do know that when some Protestants say: