This book was forbidden by the Nazi government, as it outlines a defense against the charges brought forth against Catholicism. It is a piece of Catholic reform theology that articulated a new understanding of what it means to be church. The reprinted edition features an introduction by Ulrich L. Lehner. Paul Simon (1882-1946) was professor of scholastic philosophy and apologetics in the department of Catholic theology at the University of Tubingen (1925-33). In 1933, he was appointed Cathedral Vicar in Paderborn. He was one of Germany's most distinguished theologians, as well as a proponent of ecumenism and the church's engagement with modern philosophy. Ulrich L. Lehner is Associate Professor of Historical Theology and Religious History at Marquette University. He is the author or editor of more than a dozen books on early modern religion, including Enlightened Monks (2011), and the main organizer of The Oxford Handbook of Early Modern Theology (forthcoming).