Why is Mary Called 'Mother of God'?
When early Christians read biblical passages about the Incarnation - such as Isaiah's words about the Child who would be called God (see ls 9:5) - they wondered: How exactly was Christ both human and divine? Was he simply God, only appearing to be human? Was he a human to whom God attached himself in a special way, dwelling inside him? Was he partly human and partly divine?
Ultimately, in the light of Scripture and Tradition, the Church concluded that none of the above answers is correct. An ecumenical Church council that helped to resolve the issue (Ephesus, 431 ) was provoked by a controversy over one particular question: Can we call Mary the "Mother of God"?
One prominent archbishop, Nestorius, rejected the title. He claimed that Christ was two persons - one human, one divine - joined together in Christ. Though Mary was the mother of the human person in Christ, she was not the mother of the divine Person (God the Son). So she could not rightly be called the Mother of God.
After examining this teaching, however, the Church concluded that Nestorius was mistaken. Christ was not a combination of two persons, one human and one divine. That would be close to saying that he was simply a man to whom God was joined in a uniquely intimate way - a man specially indwelled by God, like one of the biblical prophets.
Instead, the Church declared, Christ is only one divine Person - the Second Person of the Trinity. This single Person took human nature and joined it to his own divine nature, so that he possesses two natures (Jn 1:1-3, 14). But these natures don't constitute two different persons. They belong to one and the same Person, the divine Son of God. And these two natures, though not to be con- fused, cannot be separated.
In this light, the Church concluded that not only is it correct to call Mary the Mother of God, but it is important to do so. Mary is the mother of the one Person, Jesus Christ, who is the Son of God in the flesh. If we deny that she is the Mother of God, then we are denying that Christ himself is God, come down from heaven. Truly, as St. Paul declared, "God sent his Son, born of a woman" (Gal 4:4).