The Concept of Freedom identifies a tradition in western understanding of freedom and calls it the Platonic-Augustinian-Lutheran-Kierkegaardian tradition. Wenyu Xie examines the two principles in this tradition, the Platonic principle and the concept of redemption. These two principles are incompatible as concepts, as they refer to different resources of good. Yet, they co-exist in human existence as Augustine experienced. This co-existence created a tension in human existence and a dynamic in conceiving freedom. Xie analyzes the interactions between these two principles and their impact on freedom language in the history of western philosophy and theology.