Which Ecumenical Council was convened in 381 AD?

The Second Ecumenical Council, known as Constantinople I, was indeed convened in 381 AD. This council was a significant gathering of bishops that took place in the city of Constantinople (modern-day Istanbul). It primarily aimed to address various issues concerning the Nicene Creed, affirming and expanding upon the decisions made at the First Ecumenical Council held in 325 AD at Nicaea.

One of the major outcomes of the Constantinople I Council was the clarification of the nature of the Holy Spirit within the Christian doctrine, affirming the divinity of the Holy Spirit and establishing a more comprehensive understanding of the Trinity. The council also played a critical role in condemning Arianism, a heresy that denied the divinity of the Son, which was central to the theological debates of the time.

The other councils mentioned, such as the Council of Ephesus, which convened in 431 AD, focused on the nature of Christ and the relationship between His divine and human nature, and the Council of Chalcedon in 451 AD clarified Christological dogmas. Nicaea II, held in 787 AD, addressed issues related to iconoclasm. All these councils occurred at later dates than 381