First Council of Ephesus
The First Council of Ephesus took place in 431 AD and was convened by the Roman Emperor Theodosius II. It aimed to address the controversy surrounding the nature of Christ and the teachings of Nestorius, the Patriarch of Constantinople, who proposed that Christ had two separate natures. The council ultimately declared Nestorius's views heretical and affirmed the title of Theotokos (God-bearer) for the Virgin Mary.
The council was significant in shaping early Christian doctrine and solidifying the belief in the unity of Christ's divine and human natures. It also led to the condemnation of Nestorius and the establishment of the Cyril of Alexandria as a key figure in defending the council's decisions. The outcomes of this council had lasting effects on the development of Christian theology.