First Council of Constantinople main subject Arian controversy
Background
When Theodosius ascended to the imperial throne in 380, he began on a campaign to bring the Eastern Church back to Nicene Christianity. Theodosius wanted to further unify the entire empire behind the orthodox position and decided to convene a church council to resolve matters of faith and discipline.: 45  Gregory Nazianzus was of similar mind, wishing to unify Christianity. In the spring of 381 they convened the second ecumenical council in Constantinople.