I finished reading the Franz Posset book the other week. Posset (if you don't know) is a German Catholic who came to the US and studied at Marquette for his Ph.D- meaning we have something in common! I think Posset is a fine scholar and I was pleased to see Concordia publish him. I'm going to write a larger review of for LOGIA (along with his book Pater Bernhadus, which I used for an article I just finished), but I'll give a preliminary report here.
First, I liked the book's general approach to the sources and to understanding Luther. The difficulty with much Luther research has been the long hangover from the Luther Renaissance. The chief weakness of the Luther Renaissance (methodologically speaking) is the location of the origin of the Lutheran Reformation in a series of isolated psychological experiences that Luther had. This is a holdover from the Romantic theory of "Genius" and Schleiermacher's concept of religious experience. Rather, Posset seeks the origin of the Reformation in Luther's monastic-humanistic culture. Luther's concept of scriptural study is highly monastic (oratio, meditatio, tentatio). Similarly, the origin of the indulgence controversy is probably to be found in conflicts between the Dominicans and the Augustinians in religious practice (earlier Staupitz had prompted Luther to write against the rosary promoted by the Dominicans). He also helpfully observes that in entering the monastery, it is unlikely that Luther's only goal was the mortification of the flesh. The pursue of humanistic learning was also important. The Augustinians were known for humanistic learning. Luther brought books with him into the monastery. If mortification had been his sole purpose, there where were other groups of monks/friars in the area that were more into the mortification of the flesh.
I do nevertheless have some problems with some of Posset's methodological decisions. Posset isn't willing to put stock in the Table Talk at all unless verified by a citations from a authentic work of Luther. I think this is a little over the top. Hence, he wouldn't put any stock in the story Luther tells of getting caught in the storm and making a vow to St. Anne. I again, agree that the Table Talk isn't 100% reliable and at times it's very dishonest. Nonetheless, I think that his criterion is too strict. For one thing, it's hard to see why a later Lutheran would make this up and insert this story into Luther's mouth. Also, it's difficult to see why Luther would all of a sudden magically enter the monastery to his family's surprise without having an experience like this. Posset notes that there was a plague in Erfurt (which probably explains why Luther left and went to see his parents), but it doesn't totally explain the transformation. I personally think if you combine the two factors, and then observe that Luther was like many people in the later Middle Ages worried about the end of the world, then it's a coherent historical explanation.
Of course, discounting this story and generally downplaying the spiritual distress that Luther felt in favor of a model where Luther is really the champion of reviving an earlier monastic spiritulity is really part of a covert theological agenda. Ultimately Posset wants to smooth down the break between Luther and Medieval Catholicism so as to make room for ecumenical appreciation and reunification. In fact, it's not all that covert because he outright says that's part of his goal! Luther comes off in his study as strangely well adjusted (compared with his own reckoning years later!). Luther is Friar with a little bit of a bad conscience (sort of) and who loves humanistic learning and spiritual authors. Again, trying to avoid one ditch (Luther Renaissance) he's fallen into the other. Luther's spiritual experience cannot be isolated as the basis of the Reformation, but neither can it be discounted.
As part of this agenda, he (in my opinion) also overemphasizes the influence of Bernard of Clauirvaux on Luther. He claims that Bernard was even more influential than Augustine on the Reformer. Having both read some of his articles on the subject and his book, I'm not all that convinced. Much of the similarity he sees between Bernard and Luther are things they share from the common stream of monastic spirituality and Augustinianism. Similarity is not influence, which is terribly hard to demonstrate. The best he can really do is show similarity and make reference to Melanchthon's biography and a few references in Luther's works.
Even more, he doesn't get justification by faith and why it's different than justification by grace. His entire ecumenical pitch is in fact based on a confusion of the two and his lack of understanding as to why Luther is so utterly different than Bernard. For this reason, he seems to me to fall into the category of those Catholic Luther scholars who have a high view of Luther, but don't really understand him and therefore have a naive idea that they are showing how the difference between us and the Church of Rome are trivial- when they're not! In this category I would place Pesch, Wicks, and Bell.
In spite of this, overall, the book was fully of many fine insights and I highly recommend it.