The development of doctrine (for there was development from the very beginning) went on in parallel lines in East and West. It is true that the great Trinitarian and Christological heresies arose in the East, and that often for a time they seemed to swallow up great parts of those Churches. This produced a temporary schism; but in every case the East at last rejected the heresy as the West had done; some heretics remained separate from the great body of Christians, but between the main parts of the Church union was restored and the heresy was equally condemned by all. We have seen that Nestorianism and Monophysism produced the greatest and most lasting effects. Since the 5th century great bodies of Christians have remained separate from both Rome and Constantinople. The Nestorians use the Nicene Creed, accept the first two general councils, but, of course, reject the third (Ephesus, 431). Still greater schisms were caused by Monophysism. The Copts in Egypt, Jacobites in Syria, and the Armenian Church all look upon the Council of Chalcedon (451) as an abomination. We must then leave these bodies out of account. We have only to consider the faith of what we may call the Orthodox Eastern Churches, that is, those in communion with Constantinople and, until the 9th century, in communion with Rome.[1] Both East and West then used the same creeds. What we call the Apostles' Creed is a Roman baptismal form, but Eusebius of Cæsarea († c 340), Marcellus of Ancyra († 372), St. Cyril of Jerusalem († 385) and other Eastern bishops drew up practically identical creeds.[2] The great test of Orthodoxy was the Nicene Creed, first drawn up at Nicæa, then modified considerably by the First Council of Constantinople. This creed was used officially by all Orthodox Churches, Eastern and Western.[3] It is still recited in our liturgy and in theirs. It is, however, well known that the addition of a word to this creed in the West afterwards became and still is the chief charge made against us by the East. We shall come back to the question of
