Which factors have driven or at least significantly influenced the history of Christianity? In addition to the ecclesiastical, political, social and cultural atmosphere of individual epochs, it is a large number of theological minds who have acted as driving forces and initiators of Christianity. This book highlights the biography and theological work of 15 selected theological minds from the 1st to the 20th century. In an easily understandable presentation, the arc is stretched from Paul to Origen, Augustin, Anselm of Canterbury, Hildegard von Bingen, Thomas Aquinas, Martin Luther, Ulrich Zwingli, Philipp Melanchthon, Johannes Calvin to Friedrich DE Schleiermacher, Albert Schweitzer, Karl Rahner , Dietrich Bonhoeffer and Karl Barth. The limitation to portraits of these theologians at the same time marks the exemplary character of the book: Not striving for completeness and lexical detail, the theological heads depicted also represent the epochs in which they lived. The interactions between the individual theologians and the challenges of their time are illustrated in a narrative manner. On the horizon of the Reformation anniversary in 2017, the view and understanding of the diversity of Christianity will be opened up at the same time. As their effect, on the one hand Protestants, for example through the perception of Thomas Aquinas and Karl Rahner, and on the other hand Catholics, for example through the new discovery of Johannes Calvin and Karl Barth, can discover essential insights for their own Christianity. In this respect, the book can also be seen as a suggestion to appreciate the diversity of Christianity and its ecumenicity.