Luther: God has formed the soul and body of the Virgin Mary full of the Holy Spirit, so that she is without all sins

This Luther quote was left as a comment on my blog as proof of Luther's later view on the immaculate conception:

1544: "God has formed the soul and body of the Virgin Mary full of the Holy Spirit, so that she is without all sins."

This quote was said to have come from 1544, a few years before Luther's death. There it is! Proof that Luther believed in the Immaculate Conception of Mary late in his life!

For instance, this web page states: "In 1544 (just two years before his death), he wrote: 'God has formed the soul and body of the Virgin Mary full of the Holy Spirit, so that she is without all sins.'" This same information (and date of 1544) made it into this book in two different places. Wiki also uses it. We'll see this quote does not prove Luther believed in Mary's Immaculate Conception, either in 1544, or in this quote. 

Documentation
The quote may have originally been taken from Thomas A. O'Meara, O.P., Mary in Protestant and Catholic Thought (New York: Sheed & Ward, 1966). O'Meara also appears to be the culprit behind the incorrect date of 1544. On page 118 he states,

In 1532 [Luther] denied any notion of a special conception of Mary. "Mary is conceived in sin just like us. . . ."20 Finally, about this time in an undated letter, Luther agrees with Staupitz' comment that the Immaculate Conception is a "fraud." The subsequent years offer quotations which advocate the doctrine of Mary's sanctification in conception along with passages which could be interpreted as denying it. It is likely, but not certain, that he eventually denied the Immaculate Conception.

Notice footnote #20. On page 139, footnote #20, O'Meara says:

WA 36, 141. "Don't dispute about the Immaculate Conception. . . ." Letter to Kaspar Crucigar, May 1, 1541, cited in Tappolet, op. cit.,p 31. Although in 1532 Luther says that Mary was conceived in sin, in 1544 he says: "God has formed the soul and body of the Virgin Mary full of the Holy Spirit, so that she is without all sins, for she has conceived and borne the Lord Jesus." (WA 52, 39): Elsewhere, "All seed except Mary was vitiated." (WA 39, II, 107). The problem of Luther's final opinion remains to be solved.

O'Meara got the date wrong. It's from the early 1530's (1532,1533, or possibly 1534), not 1544. The reason for the confusion is this author is citing a collection of sermons published in 1544 (Luther's House Postil). WA 52:39 can be found here. The text being cited appears to be: 

The House Postil has been translated into English. 

Context

In the papacy they used to tell a story: The devil once came to church to mass, and when in the confession of the Christian faith, which they called the Patrem, they sang the words: " Et homo factum est"— the Son of God was made man—and the people did not kneel down but stood, he struck one on the mouth, rebuked him and said: You ruffian, are you not ashamed that you stand here like a stock, and do not fall down for joy? If the Son of God had become our brother, like yours, we would not know what to do for joy.

I do not think that this is true ; for the devil is too decided in his enmity to us and the Lord Jesus ; but this is true, that he who conceived this story had the right spirit, and well understood how great an honor was conferred upon us in that the Son of God became man; not like Eve nor Adam, who was made of the earth; but He is still more nearly related to us, since He was born of the flesh and blood of the Virgin Mary, like other men, except that the virgin was alone, and being sanctified by the Holy Spirit, conceived this blessed fruit without sin and by the Holy Spirit. In other respects He is like unto us, and a natural Son of a woman.

Adam and Eve were not born, but created. God made Adam out of the dust of the earth, and the woman of his rib. How much nearer is Christ to us than Eve to her husband Adam, since He is truly our flesh and blood. Such honor we should highly esteem and well take to heart, that the Son of God became flesh, and that there is no difference at all between His and our flesh, only that His flesh is without sin. For He was so conceived of the Holy Ghost, and God poured out so richly His Holy Spirit into the soul and body of the Virgin Mary that without any sin she conceived and bore our Lord Jesus.  Aside from this, in all other respects, He was like other men; He ate, drank, was hungry, thirsty, cold like other men. Such and similar natural infirmities, which have descended upon us by reason of sin, He, who was without sin, bore and had like unto us, as St. Paul says: " He was made in the likeness of men, and found in fashion as a man." [source]

Alternate English translation:

You see, he was conceived by the Holy Spirit, and God so filled the flesh, body, and soul of the Virgin Mary with the Holy Spirit in such a way, that no sin was present in her conception and carrying of the Lord Jesus (Klug (ed.), The Complete Sermons of Martin Luther vol. 5 (Grand Rapids: Baker books, 2000), 135.

Conclusion
Once again, read this quote in context, and ask yourself if it's stating Luther believed Mary was conceived without sin, or if the subject is the conception of Christ and Mary's purification at that event. Luther's later view appears to be that at Christ's conception the Holy Spirit sanctified Mary so that the child would be born with non-sinful flesh and blood. Once again, checking a primary source reveals that even scholars like O'Meara make mistakes. In this case, he either misread the context and date, or relied on some other work that did the same. O'Meara though at least states: "The problem of Luther's final opinion remains to be solved."

Addendum
TurretinFan has put together a similar overview of helpful contexts on this matter: Immaculate Conception in Later Luther?