The division between Greek and Latin Christianity developed with the division between the Eastern and the Western Empire; Rome gained an increased authority by her resolute support of Athanasius in the Arian controversy.

The first period closes with Pope Damasus and his two successors.  The Christian bishop has become important enough for his election to count in profane history.  Paganism is writhing in death pangs; Christianity is growing haughty and wanton in its triumph.

Innocent I., at the opening of the fifth century, seems the first pope who grasped the conception of Rome’s universal ecclesiastical dominion.  The capture of Rome by Alaric ended the city’s claims to temporal supremacy; it confirmed the spiritual ascendancy of her bishop throughout the West.

To this period, the time of Augustine and the Pelagian controversy, belongs the establishment in Western Christendom of the doctrine of predestination, and that of the inherent evil of matter which is at the root of asceticism and monasticism.  It was a few years later that the Nestorian controversy had the effect of giving fixity to that conception of the “Mother of God” which is held by Roman Catholics.

The pontificate of Leo is an epoch in the history of Christianity.  He had utter faith in himself and in his office, and asserted his authority uncompromisingly.  The Metropolitan of Constantinople was becoming a helpless instrument in the hands of the Byzantine emperor; the Bishop of Rome was becoming an independent potentate.  He took an authoritative and decisive part in the controversy formally ended at the Council of Chalcedon; it was he who stayed the advance of Attila.  Leo and his predecessor, Innocent, laid the foundations of the spiritual monarchy of the West.

In the latter half of the fifth century, the disintegration of the Western Empire by the hosts of Teutonic invaders was being completed.  These races assimilated certain aspects of Christian morals and assumed Christianity without assimilating the intellectual subtleties of the Eastern Church, and for the most part in consequence adopted the Arian form.  But when the Frankish horde descended, Clovis accepted the orthodox theology, thereby in effect giving it permanence and obliterating Arianism in the West.  Theodoric, the Gothic king of Italy, in nominal subjection to the emperor, was the last effective upholder of toleration for his own Arian creed.  Almost simultaneous with his death was the accession of Justinian to the empire.  The re-establishment of effective imperial sway in Italy reduced the papacy to a subordinate position.  The recovery was the work of Gregory I., the Great; but papal opposition to Gothic or Lombard dominion in Italy destroyed the prospect of political unification for the peninsula.