It is well known that energy is a fundamental concept in physics. Much less well known is that it is also a key concept in Eastern Christian or Orthodox theology. This book from Dr. Stoyan Tanev--a physicist, innovation management scholar, and theologian--provides a comparative analysis of the conceptualizations of energy in Orthodox theology and in physics, and demonstrates the potential of such comparison for a better understanding of these two quite different domains of human enquiry. The book explores the rediscovery of the Byzantine Church's teaching on the Divine energies in twentieth-century Orthodox theology, and offers new insights about the key contributions of key theologians such as Sergius Bulgakov, George Florovsky, John Meyendorff, Christos Yannaras, and Thomas Torrance. Where do the understandings of energy in theology and physics meet? The author argues that the encounter between theology and physics happens at the level of quantum physics, where the subtle use of words and language acquires a distinctive apophatic dimension. His comparative approach focuses on the epistemological struggles of theologians and physicists. According to Tanev, this focus on the struggles of knowing offers a new way to look at the dialogue between science and theology.