In the year 381, the second ecumenical council (also known as the First Council of Constantinople, or Constantinople I, to distinguish it from two later councils in the same city), met to make decisions on Christian doctrine and order.

The main thing the fathers of the first Council of Constantinople would want us to say about their work is that they re-affirmed the Council of Nicaea. That’s what they came together to do, and it was something that needed doing. Although the anti-Arian cause had prevailed decisively in the first ecumenical council in 325, the middle decades of the fourth century saw the imperial church dominated by Arianism and various forms of semi-Arianism. By 381, however, the Nicene or Athanasian party had regained control, and this council convened by emperor Theodosius I made its first order of business to re-assert the creed from the Council of Nicaea.

The biggest change they made to the creed from Nicaea was to extend the article about the Holy Spirit: In 325 the bishops had merely noted, “and [we believe] in the Holy Spirit.” But in 381 they added the wonderful language calling the Spirit “the Lord and giver of life, who proceeds from the Father, who with the Father and the Son is worshiped and glorified, who has spoken through the prophets.”
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