Hans (Johann) Heinz, ThD, born 1930 in Vienna, is Professor Emeritus of Systematic Theology and Church History, currently residing in Braunau, Austria. He has served as a pastor-evangelist and academic teacher for more than forty years in his home country and in Germany, being one of the leading Seventh-Day Adventist scholars in the fields of Reformation History and Luther Studies. While teaching at the seminaries in Bogenhofen, Marienhohe, and Friedendsau, his influence guided the theological reflection of numerous students and pastors. The present volume represents his doctoral dissertation, which was originally published by Andrews University Press (1984). The theological issues addressed in this book are still of vital importance for the modern ecumenical and interchurch dialogue.