My doctoral thesis was delivered at the Pontifical Gregorian University in Rome in april 2010 and accepted by the department of theology with the assessment “summa cum laude”. It is written in german and treats in a philsophical and theological way about the question of salvation of the human being. The question is raised starting at the period of the “German Idealism” (end 18th century – beginning 19th century) in which the concept of “freedom” (main concept of the modern and postmodern philosophy of our times) began to invade the philosophical and theological thoughts. How can a human person be really free? And which freedom can this be? And what could the christian belief contribute to the inner and outer liberation?The thesis compares two main philosophical-theological thoughts of the 20th century by relating them to the German Idealism. By this the thesis treats the question of the importance of the concept of freedom in the new theology. Two thinkers are in the center of the discourse: the lutherian german-american Paul Tillich and the catholic german Walter Kasper, both addicted to the German Idealism.The special relevance of the thesis is given by the following elements:- It is not a purely historical, but an actual and up-to-date work dealing with the central question of our times: giving sense to life by freedom.- It is an ecumenical thesis as it assembles the philosophical bases of both the main churches of western Europe: the protestant and the roman-catholic church. In the same time with the aid of Paul Tillich also the experiences of the other main religions of the world are included in the train of thought.- It tries to make theology relevant for the daily life by reflecting on practical criteria for the freedom of the postmodern humans. In the backgrounds it deals with the cultural situation that is given in the “western” countries, also and especially in Luxembourg. By this it offers a reflection about the solidarity structure of our modern society.- It reflects – also by dealing with the current luxembourgish literature – upon the concrete pastoral of the Catholic Church in Luxembourg by evaluating the practice starting from the idea of real freedom.- It gives a few approaches for a life-near spirituality.