This paper approaches mystic's interpretation through a comprehensive and integrated system of existence regarding the theory of the unity of being as a central point in Ibn 'A rabı's thought. This study begins with analysis of the concepts 'sin' and 'repentance', and the theory of the unity of being in Ibn 'A rabı's texts. It also highlights how these concepts and theory were arranged to depict a systemic net of the actions and reactions in the cosmos. In the irst step, Ibn 'A rabı's doctrine is explained, and then based on the concepts such as open systems, dynamics, complexity, and chaos a discussion is developed. The result will lead us to answer the question that how Ibn ' A rabı̄justi ies the concept of sin and how his interpretation helps to understand the position of human beings in the universe. He looks at the phenomenon of human as a complex, open, chaotic system that re lects the divine attributes.