The schism with orthodoxy following the Council of Chalcedon ( 451 ) .
It has been an important Miaphysite church , and its scriptures and liturgy continue to be in Ge'ez .
Since the schism with orthodoxy following the Council of Chalcedon ( 451 ) , it has been an important Miaphysite church , and its scriptures and liturgy continue to be in Ge'ez .