325 AD
First Council of Nicaea
The First Council of Nicaea condemned Arianism and formulated the Nicene Creed, which affirmed that Christ is consubstantial (homoousios) with the Father. This was the first ecumenical council and laid the foundation for the Christian doctrine of the Holy Trinity.
381 AD
First Council of Constantinople
This council expanded the Nicene Creed, developing the doctrine of the Holy Spirit. It declared that the Holy Spirit is „the Lord and Giver of Life,” consubstantial with the Father and the Son. This was a crucial step in shaping orthodox Trinitarian theology.
431 AD
Council of Ephesus
The Council of Ephesus condemned Nestorianism and affirmed that Mary is Theotokos, emphasizing the unity of Christ’s divine and human natures. This was a significant moment in the development of Christology, though it also contributed to divisions within the Church, particularly in the East.
451 AD
Council of Chalcedon
The Council of Chalcedon issued the Chalcedonian Definition, stating that Christ is „truly God and truly man,” possessing two natures in one person. This formulation became a cornerstone of Christian orthodoxy but also led to a schism with the non-Chalcedonian Churches (e.g., the Coptic Church).
553 AD
Second Council of Constantinople
This council reaffirmed the teachings of Chalcedon and condemned Nestorian tendencies. Although it sought reconciliation with the Monophysites, it did not achieve lasting unity. It was important for solidifying orthodox Christology.
680–681 AD
Third Council of Constantinople
The council condemned Monothelitism and affirmed that Christ has two wills (divine and human), which are harmoniously united. This was the last council to address Christological issues.
787 AD
Second Council of Nicaea
The Second Council of Nicaea condemned Iconoclasm and declared that icons may be venerated, though they should not be given divine worship. This was a crucial moment in the development of the theology of icons, which holds special significance in the Orthodox Church.