Gregory was raised in a very pious (and large) Christian family of ten children; his grandmother [[Macrina the Elder]], his mother [[Emily]], his father [[Basil the Elder]], his sisters [[Macrina the Younger]] and [[Theosebia]], and his brothers [[Basil the Great]] and [[Peter of Sebaste]] have all been recognized as saints. He received a good education and taught rhetoric at one point. In 372, his brother Basil [[ordination|ordained]] him the [[bishop]] of Nyssa in Cappadocia (in present-day Turkey).
Gregory and Basil both spent much effort defending the Faith against the attacks of the [[Arianism|Arians]]. He was twice deposed
as leader of his See because of false accusations made by the heretics. His position as bishop was finally restored in 378.
The next year, 379, his brother [[Basil the Great]] died. As the two were extremely close, Gregory was very grieved at his loss. To honor his brother, Gregory wrote his funeral oration and then completed Basil's ''Hexaemeron'', a series of nine sermons, delivered during [[Great Lent]], which described and elaborated upon the [[Genesis]] account of the world's creation in six days
(Hexaemeron means "six days"). The following year, Gregory's sister [[Macrina the Younger|Macrina]] also died, and Gregory wrote a [[hagiography]] detailing her life.
About this time Gregory attended the Council of Antioch, a local [[synod]], in which he zealously defended Orthodoxy. The council was called to
rebut a [[heresy]] which denied the perpetual virginity of the [[Theotokos]] , on one hand, and other the other hand forbid worship of her as God or part of the Godhead. Gregory was simultaneously continuing to fight Arianism. Next, he attended the [[Second Ecumenical Council]] in Constantinople, which added the final section concerning the [[Holy Spirit]] to the [[Nicene-Constantinopolitan Creed]].
For the rest of his life, Gregory continued to attend church councils, discuss doctrinal matters, and combat various heresies.