Renewing Islam by Service offers a theological account of the contemporary Turkish faith-based service movement started by Fethullah G len, and placed against the backdrop of changes in modern Turkish society. The life and works of G len are analyzed against the background of developments in Turkish society, and of spiritual Islamic tendencies in the transition from the Ottoman empire to the secular republic. Pim Valkenberg includes stories of his personal experiences with supporters of this movement, in a number of different countries, and analyzes the spiritual practices and the faith-based service of this movement that is also compared to some important Christian religious movements. Fethullah G len (born 1941 in Erzurum) is sometimes mentioned as one of the most influential Islamic scholars of the twenty-first century. During his work as a scholar-preacher in Izmir in the 1970s he started to provide learning opportunities for his students. He attracted many supporters and inspired them to form communities that put their Islamic faith into practice by serving others. When the political and economic situation of the Turkish republic improved, G len and the Hizmet (service) Movement began to take initiatives in order to overcome ignorance, disunity and poverty. At the beginning of the 21-st century the Hizmet Movement ormed one of the most influential networks of Muslims, not only in Turkey but in Europe and the United States as well. G len now lives in the United States where he still inspires many groups to engage in dialogue initiatives, excellent schools, public media and service organizatons. However, these initiatives are often met with suspicion by a number of different groups - secularists as well as radical Muslims. While the Hizmet Movement has thus far mainly been studied from a social scientific perspective, this book claims that G len and the Hizmet can best be understood by researching the religious drive that empowers them. Since this book has been written by a Christian theologian, this is done in a comparative theological approach that not only shows how G len and the Hizmet Movement renew Islam by service, but also how Christians can be inspired by such a religious renewal movement.