Of all the issues that divide Catholics and Protestants, one would be hard pressed to come up with a topic more controversial than the role of the Blessed Virgin Mary in Catholic religious practice. As Catholics, we recognize Our Lady as mother of the Church and the spiritual mother of all Christians. She is identified by the Catholic Church as the "New Eve", and is thus considered the most important human figure in our salvation history second only to the "New Adam", our Lord Himself. As "Mother of God", Mary transcends in dignity all creatures, be they angels or men, because the dignity of a creature increases with closeness to God. Mary, since she is the mother of the divine person of Jesus, is closest to Him. We thus give her great honor and have dedicated many popular devotions, hymns, litanies and prayers to her.
Many Protestants, especially Evangelicals, are uncomfortable with the prominence of Mary's role in Catholic liturgical practice. Protestant converts to Catholicism routinely cite Mary as the most difficult of all Catholic teachings to accept. Protestants, in general, think that Catholics pay too much attention to Mary, and in doing so, diminish the amount of honor rightfully due to Christ. Protestants hold Sacred Scripture alone to be the final authority in terms of faith and morals, and many Catholic teachings about Mary are not directly evident in Scripture. Many Protestants therefore find Catholic devotion to Mary, at best, a little strange, and at worst, a practice bordering on idolatry.
The Catholic Church teaches four major doctrines about Our Lady: her Divine Maternity (that Mary is the mother of God), her Perpetual Virginity (that Mary remained a virgin throughout her life even after the birth of Jesus), her Assumption (that after her life, she was assumed body and soul into Heaven), and her Immaculate Conception (that Mary at her conception was preserved from the stain of Original Sin). In this post, I will begin with the doctrine of Our Lady's Divine Maternity because it is her greatest privilege from which all of her other privileges follow. It is also the simplest to explain scripturally and doctrinally.
The doctrine of Our Lady's Divine Maternity can be demonstrated scripturally in Lk 1:39-56, which depicts Mary's Visitation to Elizabeth. Elizabeth, upon hearing the greeting of Mary, is "filled with the Holy Spirit" and declares in Lk 1:43: "And why is this granted me, that the mother of my Lord should come to me?" The phrase "mother of my Lord" can only be interpreted as "mother of God." The usage of "Lord" in the New Testament refers only to God and is plainly evident by simply focusing on the context of the Visitation passages. For example, "Lord" clearly means God in Lk 1:45: "And blessed is she who believed that there would be a fulfillment of what was spoken to her from the Lord". Similarly "Lord" also clearly means God in Lk 1:46-47: "And Mary said, 'My soul magnifies the Lord, and my spirit rejoices in God my Savior.'" Moreover, Elizabeth is "filled with the Holy Spirit" when declaring that Mary is the mother of the Lord. Because she is "filled with the Holy Spirit", Elizabeth is speaking with divine authority and not personal opinion.
Mary's Divine Maternity can furthermore be demonstrated doctrinally as an inevitable consequence of the Hypostatic Union. Because the Hypostatic Union doctrine is accepted by nearly all Christian denominations (although Christians may not know exactly it by that name), it is a good framework to use when explaining the doctrine of Divine Maternity. Before we examine the Hypostatic Union however, we should understand what a nature is and a person is, and how they are related.
The terms person and nature answer two different questions about something. When we are asking "what" something is, we are asking what its nature is. For example, when we ask the question "What are you?", the answer is "a man": a nature. A nature defines what an entity's capabilities are. For example, the abilities of eating, drinking, thinking, laughing, and crying are all abilities particular to a human nature. We do not, however, have the ability to fly through the air because that ability is particular to a bird nature and not a human nature. When we are asking "who" someone is, we are asking who that person is. When we ask the question "Who are you?", the answer is "Jonathan": a person. A person is "an individual substance of a rational nature" which directs the actions of an entity. So even though a nature determines what actions are possible for an entity, it is the person that ultimately directs the actions of that entity. With this in mind, let us turn to the Hypostatic Union.
The Hypostatic Union is a theological term used with reference to the Incarnation which expresses the revealed truth that Christ is one divine person with two natures, one divine and one human. Furthermore "the two natures [human and divine] of Christ are joined 'in one [divine] person and one hypostasis' […], where hypostasis means one substance." The term "one substance" is important here. This means that the person of God the Son, Jesus Christ, was permanently united to a human nature while maintaining His divine nature. Because the properties of human nature were united to the divine person of Christ, we can say that the divine person of Christ truly became man. That Christ has two natures is essential for mankind's redemption. Because Christ became man, He was able to make Himself an adequate offering for sin on behalf of the fallen race of Adam. Because Christ is divine, His actions have infinite merit and dignity. Only an act of infinite merit and dignity could satisfy the infinite justice of God the Father and thus redeem the entire human race. If Christ were only human, His actions would only be of finite merit and therefore not sufficient to satisfy the Father's infinite justice.
Protestants, oftentimes in an effort to downplay her prominence, will argue that Mary could only have been the mother of Christ's human nature, not His divine nature, and therefore could not be the mother of God. This argument however is predicated on the invalid assumption that a mother gives birth to a nature. A mother is always the mother of a person, not a nature. A human being is a union of body and soul. Even though the eternal soul is created by God, nobody would argue that the mother is the mother of the body only. This is because mothers don't give birth to bodies; they give birth to persons. No one refers to their mother as the "mother of my body" or the "mother of my nature."
Because a mother only gives birth to a person, further attempts to downplay Mary's prominence lead one to argue that Mary could only have been the mother of Christ's human person, and therefore could not be the mother of God. Asserting that Mary gave birth to a human person, however, leads to two erroneous conclusions, both of which contradict the Hypostatic Union: either Jesus Christ was not a divine person, but one human person with two natures and therefore not God; or He was two persons, one divine and one human, coexisting with two corresponding natures. It was this latter thinking that Nestorius, bishop of Constantinople, had arrived at when he condemned the use of "Theotokos" in AD 428.
"Theotokos" (literally 'God-bearer" or "Mother of God") was a title for the Virgin Mary that was used by the Christian faithful from as early on as the 3rd century. Nestorius postulated that to call Mary the mother of God would imply that the divine nature was born of a woman, making Mary a goddess. He instead proposed the title "Christotokos" ("Mother of Christ"). Although he claimed to believe in one Christ with two natures, Nestorius described Christ as the union of two distinct persons, one human and one divine: "He who was formed in the womb of Mary was not God himself, but God assumed him." This view is theologically problematic, because if there were two persons in Christ, one human and one divine, we could not know for sure whether the divine person of God the Son died for our sins, or whether the human person did. This puts the certainty of the Redemption and thus our salvation in question. It was for these reasons that at the Council of Ephesus in AD 431 the teachings of Nestorius were declared heretical, and Mary's title "Theotokos" was reaffirmed as orthodox.
Mary is neither the mother of a human person, nor a human person that coexisted with a divine person, but the mother of the divine person of Jesus. But why do we call Mary the "Mother of God" and not just the "Mother of Jesus?" The answer to this can be found by looking to the doctrine of the Trinity which states that God is three persons in one divine nature. One consequence of this doctrine is that we can say that the Father is God, Jesus the Son is God, and the Holy Spirit is God: "But to the question 'What are you?' each [of the three persons] could but answer 'God,' because each totally possesses the one same divine nature, and nature decides what a being is." Since Mary is the mother of the divine person of Jesus, and Jesus is God, we must conclude via deductive logic that Mary is the mother of God. The conclusion is inevitable. As one writer puts it: "There is no way out of this syllogism, whose form logicians have recognized as valid since before Christ." Acknowledging Mary as the mother of God therefore directs us to acknowledge not only Christ's humanity, but His divinity as well.
Although one may logically conclude that Mary is the mother of God, it is not necessarily an easy conclusion for some to accept. One stumbling block involves an apparent problem of chronology. Many will often conclude that Mary could not be the mother of God since that would imply that she was older than God. This line of reasoning is faulty however, because it starts from the viewpoint of a temporal being (Mary) and attempts to impose temporal restrictions (the existence of a parent before a child) on an eternal being that existed before time was created. To understand Mary's Divine Maternity requires one to begin not with Mary's temporal viewpoint, but with God's eternal one. In order to become man, God the Son had to adopt the limitations of man; one limitation being that a human being is born at a certain point in time. Christ simply chose to be born at a particular point in history. Christ was thus able to choose who His mother would be, and thus would choose the most perfect of mothers for Himself. And in Jn 19:27 when Jesus upon the cross spoke the words "Behold, your Mother," He gave the human race that same most perfect of mothers; a mother deserving of our respect and devotion.
Catholics, when describing their devotion to the Blessed Mother, often use the phrase "To God through Mary," to indicate that a devotion to Mary leads one closer to God. In like manner, affirming Mary's Divine Maternity ultimately leads one to contemplate the rich mysteries of the Hypostatic Union and the Trinity, resulting in a more intimate understanding of our Lord.