Thanks to Ken Stewart of Covenant College for taking the time to review our 2011 book, The Pietist Impulse in Christianity, in the new issue of Haddington House Journal!
You’ll need to buy the issue to read the full review, since it’s not online. But in short, Stewart applauds the book on four counts: (I’ll link to my own summaries of the book’s sections if you’d like to delve more deeply)
1. Our opening chapters by Roger Olson and Peter Yoder “go a considerable distance in showing the extent to which Pietism has been misjudged, both in its original European setting and within North America.”
2. The succeeding sections, on German Pietism and Pietism interacting with the Enlightenment, begin to show, in Stewart’s opinion, “the diversity of views encompassed within the Pietist movement and to grasp how, over time, there would be elements of this evangelical tradition which would serve to call into question the integrity of the movement as a whole.” (e.g., the “Pietist devotion” of Friedrich Schleiermacher and Søren Kierkegaard “did not unerringly keep them on an even keel”)
3. Our sections on Scandinavian and North American expressions of the Pietist impulse illustrate how “Pietism had moved well beyond the ‘church within a church’ model practiced by European believers who were solicitous for the quickening of their state churches…”
4. Stewart agrees that our essays on Pietism and missions make the case that the history of Protestant missions does not begin with William Carey: “It is past time for us to pay proper tribute to this movement which was the actual Protestant missionary pace-setter for three quarters of a century before Carey was prompted to attempt a mission to India.”
The review concludes on an ambivalent note, with Stewart grateful “for the great, though under-recognized, contribution that Pietism has made to world Christianity” and yet concerned about “what is to become of a Pietist stream in Christianity which, when severed by controversy or immigration from European Pietist roots, becomes a virtual stream of world Christianity in and of itself with no clear doctrinal heritage to call its own.”
The Pietist Schoolman 
I wonder to what extent modern Pietism has common cause with radical free grace theology or post-evangelicalism. Some outspoken post-evangelicals may challenge orthodox theology more than Pietists, but others would just downplay theological hair-splitting, which fits well with Pietism. Radical free grace theology, in some its forms, is like Lutheranism without the Book of Concord, which makes it very similar to Pietism.