Luther: "She is rightly called not only the mother of the man, but also the Mother of God ... It is certain that Mary is the Mother of the real and true God."

Over the years I've worked through a Roman Catholic article that "documents" the Mariology of the Reformers. The article is sometimes called, "The Protestant Reformers on Mary." Here is a Martin Luther quote that's usually included:

Mary the Mother of God. Throughout his life Luther maintained without change the historic Christian affirmation that Mary was the Mother of God: "She is rightly called not only the mother of the man, but also the Mother of God ... It is certain that Mary is the Mother of the real and true God."[Martin Luther, Weimar edition of Martin Luther's Works, English translation edited by J. Pelikan [Concordia: St. Louis], volume 24, 107].

If you're puzzled as to why this quote is supposed to be shocking to Protestant eyes, it means you're probably not a garden variety fundamentalist that has theological spasms whenever you come upon the phrase "Mother of God." Luther used this phrase occasionally, but did not use it as a term of invocation or worship. When he used it, it was either an expression of the common vernacular of the sixteenth century, a term of respect for her as someone profoundly used by God in a significant way, or it was primarily to say something about Jesus, not Mary. The context below will bear this out. 

Documentation

As is often the case with Roman Catholic propaganda, the documentation is spurious. Someone mixed together the English and German / Latin editions of Luther's writings. This quote isn't from WA 24 in the Weimar edition, it's from volume 24 of the English edition. 

The origin of this quote may be from a 1992 Catholic Answers article by Father Mateo, CRI's Attack on Mary: Part 1. The article states, 

Throughout his life Luther used and defended Mary’s title “Mother of God” against all comers. “She is rightly called not only the mother of the man, but also the Mother of God. . . . It is certain that Mary is the Mother of the real and true God.”(Jaroslav Pelikan, ed., Luther’s Works (St. Louis: Concordia), vol. 24, 107.) (I wonder about CRI’s consistent failure throughout to mention Protestant sources in praise of Mary.)

It's possible Father Mateo actually mined out this quote. It looks like someone took Mateo's words, changed them a little bit, adding Weimar to the documentation.

Context
We say of every human being that he eats, drinks, digests, sleeps, wakes, walks, stands, works, etc., although the soul participates in none of these activities, but only the body. And yet this is said of the entire person, who has a body and a soul. For it is one person, by reason not only of the body but of both the body and the soul. Again, we say that man thinks, deliberates, and learns. According to his reason or soul, he can become a teacher or master, a judge, councilor, or ruler. Neither the body nor any one of its members gives him this competence. And yet we say: “He has a clever head; he is sensible, learned, eloquent, artistic.” Thus it is said of a woman that a mother carries, bears, and suckles a child, although it is not her soul but only her body that makes her a mother. And still we ascribe this to the entire woman. Or if someone strikes a person on the head, we say: “He has struck Hans or Greta.” Or if a member of the body is injured or wounded, we think of the whole person as being wounded.

I am using these simple illustrations to demonstrate how two distinct natures must be differentiated in the Person of Christ and yet how this still leaves the Person a whole and undivided entity. Whatever Christ says and does, both God and man say and do; yet each word and action is in accord with the one or the other nature. He who observes this distinction is safe and on the right path. He will not be led astray by the erroneous ideas of heretics, ideas which come into being solely because they do not properly join what belongs together and is united, or because they do not properly separate and distinguish what must be distinguished.

Therefore we must adhere to the speech and expressions of Holy Writ and retain and confess the doctrine that this Christ is true God, through whom all things are created and exist, and at the same time that this same Christ, God’s Son, is born of the Virgin, dies on the cross, etc. Furthermore, Mary, the mother, does not carry, give birth to, suckle, and nourish only the man, only flesh and blood—for that would be dividing the Person—but she carries and nourishes a son who is God’s Son. Therefore she is rightly called not only the mother of the man but also the Mother of God. This the old fathers taught in opposition to the Nestorians, who objected to calling Mary “Mother of God” and refused to say that she had given birth to God’s Son.

Here we must again confess with our Creed: “I believe in Jesus Christ, God the Father’s only Son, our Lord, born of the Virgin Mary, suffered, was crucified, died.” It is always one and the same Son of God, our Lord. Therefore it is certain that Mary is the mother of the real and true God, and that the Jews crucified not only the Son of Man but also the true Son of God. For I do not want a Christ in Whom I am to believe and to whom I am to pray as my Savior who is only man. Otherwise I would go to the devil. For mere flesh and blood could not erase sin, reconcile God, remove His anger, overcome and destroy death and hell, and bestow eternal life." (LW 24:106-107).

Conclusion
Here, Luther's using the rich Christ-centered usage of Theotokos (Mother of God) when discussing the incarnation or Christ’s Deity. I and conservative Protestant theology would agree with him.  This quote may be a "shocker" to fundamentalist types, but not to the Lutheran or Reformed. Notice that Luther mentions the Nestorians. I guess if Roman Catholic apologists are interacting with modern Nestorians that are fond of Luther, using this Luther quote could be useful.

When Rome's defenders bring up the phrase, "Mother of God," they have gone beyond what Luther usually means by it, attaching excessive veneration. What was once a rich theological term expressing a doctrinal truth about Christ developed into a venerating praise to Mary. If you agree to use this term in dialog with a Roman Catholic apologist, use it like Luther did. Use it to say something about Jesus Christ.