Book excerpt: The time has come for Pietism to revitalize Christianity in America. Historian Christopher Gehrz and pastor Mark Pattie argue that the spirit of Pietism, with its emphasis on our walk with Jesus and its vibrant hope for a better future, holds great promise for the church today. Modeled after Philipp Spener's Pia Desideria, this concise and winsome volume introduces Pietism to a new generation.