The book is a little bit repetitive since it is a collection of various lectures that have been edited and gathered into a book. But, having said that, many of the points are certainly worth repeating for Hefner presents a highly attractive account of how nature and culture can be viewed from the light of theology. His main starting point is firstly that human beings have developed according to evolution, secondly, that myths and faith is essential for living a flourishing human life (although our relation to myths need to be re-oriented in these days) and, thirdly, that nature and culture are simply 'two streams of information', both vital for human survival. In some ways it could be said that genes and culture are simply two different ways in which evolution has been able to store information.
Hefner's main point is that humans are created co-creators and as such have a unique responsibility for creation - the only species with the ability to change the whole earth (sloppily put, Hefner writes it better).