Final answer:
St. Gregory of Nyssa defended the title "Theotokos" for Mary, meaning "God-bearer" or "Mother of God."
Step-by-step explanation:
"Theotokos" is the title St. Gregory of Nyssa staunchly defended for Mary, advocating it during the Council of Ephesus in 431. This Greek term translates to "God-bearer" or "Mother of God." Its significance goes beyond a mere honorific; it affirms the divine nature of Jesus Christ, emphasizing Mary's role in bearing and giving birth not just to a human being, but to the Son of God in His entirety. This title became pivotal in the early church's debates about the nature of Christ, particularly countering the Nestorian heresy, which sought to separate Jesus' divine and human natures. By acknowledging Mary as Theotokos, the church affirmed the unity of Christ's personhood, encapsulating the belief in the Incarnation—God becoming man through her. St. Gregory's defense secured the theological understanding of Mary's pivotal role in Christian doctrine.
St. Gregory of Nyssa defended the title "Theotokos," meaning "God-bearer" or "Mother of God