Why do Catholics call Mary the Mother of God?
Because this title for Mary summarizes our belief that Jesus is true God and true man! The initial dispute over the use of the title, in fact, going back to the early fifth century, centered on a question about Christ’s divinity: Was the baby born to Mary truly God, or did God merely “dwell” in a human body? The controversy was ignited by Nestorius, the Bishop of Constantinople, who, refusing Mary the title Mother of God (Greek Theotokos), preferred to call her instead simply the Mother of Christ (Christotokos), because he insisted the baby born in Bethlehem could not rightly be called God.
The Bishops at the Council of Ephesus, called to settle this dispute in 431, denounced Nestorius’ teaching and definitively declared, as Christians had always believed, that Jesus was indeed both truly divine and truly human. The Council, moreover, officially sanctioned Mary’s title Mother of God, for this title safeguarded what Christians believed about Jesus. That He had a mother proved He was truly human. That Mary’s child was God proved He was truly divine. Logically, one could say that since Jesus is God; and Mary is His Mother; Mary, therefore, is the Mother of God.
This controversy was reignited during the Protestant Revolt in the seventeenth century, and continues today. It is troubling, to say the least, that a full millennium-and-a-half since the defeat of Nestorianism the title Mother of God remains a source of controversy among Christians. When Protestants hear Catholics call Mary the Mother of God they assume we are ascribing to her too lofty a role, elevating her as being somehow above to God. Catholics do not call Mary the Mother of God because we believe she was above God, however, but, very simply, because we believe the person whom she bore in her womb was God. By the same token, Catholics are perplexed by Protestants’ refusal to call Mary the Mother God, all the while proclaiming the divinity of Her Son.
To assert that Mary was only the mother of Jesus’ human nature is heresy. For, as Catholic apologists have rightly pointed out, Mary gave birth to a person, not a nature (cf. Karl Keating, Catholicism and Fundamentalism, Ignatius Press, 1988, p. 277). Because the divine maternity of Mary, and all the Church’s official beliefs about her, ultimately instruct us about Jesus, the denial of a truth about her invariably leads to some denial of Him.
The real danger in rejecting Mary’s divine maternity is that it draws too much of a distinction between Christ’s dual natures, effectively dividing Him into two persons: the divine Jesus and the human Jesus. More or less, this is what Nestorius did, openly admitting on one occasion he would have difficulty calling the Infant Jesus God. Ultimately, Nestorianism threatened belief in the Redemption. For if such a distinction could be drawn between Christ’s divinity and humanity, then it could be said–even must be said–that God did not actually die for our sins. If the babe born to Mary was not truly God, then the man who was nailed to the Cross and rose from the dead could not have been either!
Do we find the title Mother of God in the Bible? No, but neither do we find “Trinity” nor “Bible,” for that matter, either. While the specific title itself does not appear in the Bible, though, it is biblical, meaning it agrees with what the Bible teaches. Quoting the prophet Isaiah, for example, Matthew writes, “‘Behold, a virgin shall conceive and bear a son, and his name shall be called Emmanuel’ (which means, God with us)” (Matt. 1:23). We see Mary’s divine maternity, furthermore, implied in Elizabeth’s greeting of her in the Gospels: “And why is this granted me, that the mother of my Lord should come to me?” (Luke 1:43).
Certainly the title Mother of God is expressed in historical Church documents dated well before the era of the Council of Ephesus and, interestingly enough, in the writings of Christians teachers descending from the Apostle John, the one to whom Jesus had entrusted Mary at the time of His death (cf. John 19:27). Ignatius of Antioch, who learned directly from John, wrote in about the year 107, “For our God, Jesus Christ, was conceived by Mary” (Letter to the Ephesians 18:2). Irenaeus, whose teacher Polycarp of Smyrna was also a disciple of the Evangelist, wrote in the latter half of the second century, “The Virgin Mary, … being obedient to His word, received from an angel the glad tidings that she would bear God” (Against Heresies 5:19:1). Irenaeus’ student, Hippolytus (d. 235), referred to Our Lady as “the spotless and God-bearing Mary” (Discourse on the End of the World).
From around 250, we have the prayer Sub Tuum Praesidium, which cries out, “Under your mercy we take refuge, O Mother of God.” Alexander, the Bishop of Alexandria, said in 324 that the body of Our Lord was “derived from Mary the Mother of God” (Encyclical Letter to Another Bishop Alexander and to All Non-Egyptian Bishops 12). Around 350, Cyril of Jerusalem declared, “The Virgin Mother of God bears witness [to Christ]” (Catechetical Lectures 10:19). The Roman Emperor Julian the Apostate (reign. 361-363) complained that Christians “never stop calling Mary ‘Theotokos’ [or God-bearer]” (quoted by Cyril of Alexandria, Defense of Christianity Against the Books of the Impious Emperor Julian). Around 365, Athanasius called Mary “the Mother of God” (Incarnation of the Word of God 8). Ephraim the Syrian (d. 373) did so as well (cf, Songs of Praise 1:20). In 382, Gregory of Nazianzus said quite matter-of-factly, “If anyone does not agree that Holy Mary is the Mother of God, he is at odds with the Godhead” (Letter to Cledonius the Priest, Against Apollinaris 101).
Finally and ironically, even Martin Luther (d. 1546), the father of Protestantism, defended Mary’s divine maternity. In his Commentary on the Magnificat, for example, he wrote, “Men have crowned all her glory into a single phrase: the Mother of God. No one can say anything greater of her, though he had as many tongues as there are leaves on the trees.”