Because the Catholics altered the faith of Christ and became heretics by accepting the filioque clause. How dare - to the Orthodox - the Pope alter what the ecumenical councils said can not be altered!
This implies that all the Western Fathers, who unanimously accepted the filioque, were all heretics.
How dare - to the Orthodox - the Pope alter what the ecumenical councils said can not be altered!
Ephesus said that it was okay to add explanations to the Creed.
It seems fitting that all should assent to this holy creed. It is pious and sufficiently helpful for the whole world. But since some pretend to confess and accept it, while at the same time distorting the force of its expressions to their own opinion and so evading the truth, being sons of error and children of destruction, it has proved necessary to add testimonies from the holy and orthodox fathers that can fill out the meaning they have given to the words and their courage in proclaiming it.
It really doesn't matter what its about.
You need us much more than we need you.
And if you fall by the wayside...no sweat here.
Good luck against Islam
You'll need it.