Issues Etc. is an awesome program. I cannot recommend it highly enough. Last Sunday, the program covered Pietism. If you haven't had the chance to listen to it, go listen now. Todd Wilken interviewed Dr. Rod Rosenbladt, a man whose background was Pietism and how it drove him to atheism. Thank Go He rescued him from his atheism and brought him into the bounds of Lutheran Orthodoxy. Also, you might want to read the following article by Craig Parton.
The New White-Wine Pietists