The language of mutual condemnation used by the two rival synods at Serdica was strong. There was no inclination on either side to make concessions or to plead for mutual toleration on some such ground as the transcendent mysteriousness of the matters on which east and west were expressing disagreement. Moreover, the western bishops were in a substantial degree the instruments of Constans' ambitions to be rid of his brother Constantius II and to rule the entire empire in the manner of his father, not merely two- thirds of it. Underlying the dispute was an emperor's aspiration to control the east as he was already master of the west. At the same time there was a looming tension between the Roman claim that the bishop of Rome had a unique authority to decide dogmatic and indeed any church questions without needing to be respectful towards synods of the eastern churches and, on the other hand, the Greek assumption that the Roman see was certainly to be respected but should never overrule the customary procedures and synodical authority of Greek assemblies. Naturally it was non-controversial that in questions of fundamental doctrine the eastern and western churches were and at all times needed to be in complete agreement. There might, of course, be room for discussion on the question of defining 'fundamental'. That issue once surfaces in Origen, but did not become prominent until the Pelagian controversy of the fifth century and then only briefly.
The internal dissensions of the Christians offered strong contrast with the peaceful rapprochement of Church and Empire that the Constantinian dynasty (other than Julian) wanted to encourage. That programme of reconciliation derived impetus and drive from the Christian aspiration to be the one faith of every nation and tribe under heaven. A missionary determination to make proselytes underlay the Church's gospel. Constantine the Great had thought this a profoundly congenial imperial theme, since he could use monotheism to justify his own supreme rule (as in Eusebius' panegyric On the Life of Constantine). He liked to be told that he was the representative on earth of the unique supreme Deity. When people commonly called the empire by the name oikoumene, the inhabited world, it could seem natural to