Well, gee, it’s like this: in 1302 A.D. the Catholic Church AND the Greek Church in schism (salvation in one still recognized by the other) were the Christian church.
The Church had by then experienced a number of heretical breakaways. Pope Boniface invalidated them with his statement.
BTW, there were no Protestants then.
So, “Ex Cathedra” is a personal opinion?
Well, the EO say Rome is in schism and Rome says the EO is in schism.
Can y’all make up your minds and let us know what y’all decide?