Saint Gregory, Bishop of Nyssa, was a younger brother of St Basil the Great (January 1). His birth and upbringing came at a time when the Arian disputes were at their height. Having received an excellent education, he was at one time a teacher of rhetoric. In the year 372, he was consecrated by St Basil the Great as bishop of the city of Nyssa in Cappadocia.
St Gregory was an ardent advocate for Orthodoxy, and he fought against the Arian heresy with his brother St Basil. Gregory was persecuted by the Arians, by whom he was falsely accused of improper use of church property, and thereby deprived of his See and sent to Ancyra.
In the following year St Gregory was again deposed in absentia by a council of Arian bishops, but he continued to encourage his flock in Orthodoxy, wandering about from place to place. After the death of the emperor Valens (378), St Gregory was restored to his cathedra and was joyously received by his flock. His brother St Basil the Great died in 379.
Only with difficulty did St Gregory survive the loss of his brother and guide. He delivered a funeral oration for him, and completed St Basil's study of the six days of Creation, the Hexaemeron. That same year St Gregory participated in the Council of Antioch against heretics who refused to recognize the perpetual virginity of the Mother of God. Others at the opposite extreme, who worshipped the Mother of God as being God Herself, were also denounced by the Council. He visited the churches of Arabia and Palestine, which were infected with the Arian heresy, to assert the Orthodox teaching about the Most Holy Theotokos. On his return journey St Gregory visited Jerusalem and the Holy Places.
In the year 381 St Gregory was one of the chief figures of the Second Ecumenical Council, convened at Constantinople against the heresy of Macedonius, who incorrectly taught about the Holy Spirit. At this Council, on the initiative of St Gregory, the Nicean Symbol of Faith (the Creed) was completed.
Together with the other bishops St Gregory affirmed St Gregory the Theologian as Archpastor of Constantinople.
In the year 383, St Gregory of Nyssa participated in a Council at Constantinople, where he preached a sermon on the divinity of the Son and the Holy Spirit. In 386, he was again at Constantinople, and he was asked to speak the funeral oration in memory of the empress Placilla. Again in 394 St Gregory was present in Constantinople at a local Council, convened to resolve church matters in Arabia.
St Gregory of Nyssa was a fiery defender of Orthodox dogmas and a zealous teacher of his flock, a kind and compassionate father to his spiritual children, and their intercessor before the courts. He was distinguished by his magnanimity, patience and love of peace.
Having reached old age, St Gregory of Nyssa died soon after the Council of Constantinople. Together with his great contemporaries, Sts Basil the Great and Gregory the Theologian, St Gregory of Nyssa had a significant influence on the Church life of his time. His sister, St Macrina, wrote to him: "You are renowned both in the cities, and gatherings of people, and throughout entire districts. Churches ask you for help." St Gregory is known in history as one of the most profound Christian thinkers of the fourth century. Endowed with philosophical talent, he saw philosophy as a means for a deeper penetration into the authentic meaning of divine revelation.
St Gregory left behind many remarkable works of dogmatic character, as well as sermons and discourses. He has been called "the Father of Fathers."