Follow up question: to what extent would these Protestants have considered the Eastern Orthodox to be Christians? What about the Oriental Orthodox and the Church of the East (non-Chalcedonians)?

Many of these Orthodox churches are members of the World Council of Churches with many Protestant churches (but not the Roman Church), indicating some kind of ecclesiastical collegiality between Protestants and Orthodox. Would some Protestants have considered the Orthodox to be Christians, but not Roman Catholics? If so, wouldn't that be completely non-sensical theologically?