He argues, throughout the remainder of the book, starting from chapter four, against the idea of a 'purpose' to life, arguing against the religious brigade, who are determined to refute the theory of evolution, and all the evidence for it. He uses his precious DNA to show, as he explains it, "The universe we observe has precisely the properties we should expect if there is, at bottom, no design, no purpose, no evil and no good, nothing but blind, pitiless indifference...DNA neither knows nor cares. DNA just is. And we dance to its music" (Dawkins, 1995).
In chapter five, Dawkins introduces what he terms 'thresholds',
The book is anti-religious, anti-"God's creation myth," through its author's stark atheist beliefs, and his belief that evolution, and only evolution, can explain the myriad forms of complex life we have on earth today. As he says, in the final chapter, only the theory evolution can explain something as complex as an eye, using examples to show that slight changes in complex systems can indeed be advantageous (e.g., the honeybee dance), and only science can explain life, and offer truly believable facts: "Scientific beliefs are supported by evidence, and they get results. Myths and faiths are not and do not" (Dawkins, 1995). His final discussions in the book are slightly depressing, "Nature is not cruel, only pitilessly indifferent. This is one of the hardest lessons for humans to learn. We cannot admit that things might be neither good nor evil, neither cruel nor kind, but simply callous - indifferent to all suffering, lacking all purpose" (Dawkins, 1995).