Richard Dawkins deals with some of the philosophical and social ramifications of the theory of evolution. Dawkins starts out in Kenya, speaking with palaeontologist Richard Leakey. He then visits Christ is the Answer Ministries, Kenya's largest Pentecostal church, to interview Bishop Bonifes Adoyo. Adoyo has led the movement to press Kenya's national museum to sideline its collection of hominid bones pointing to man's evolution from ape to human.[5] The collection includes the Turkana Boy discovered by Kamoya Kimeu, a member of a team led by Richard Leakey in 1984. Dawkins discusses social darwinism and eugenics, explaining how these are not versions of natural selection, and that 'Darwin has been wrongly tainted'. He then meets with evolutionary psychologist Steven Pinker to discuss how morals can be compatible with natural selection. He goes on to explaining sexual selection, with peafowls as an example. To find out whether sexual selection plays a role for altruism and kindness among humans, he visits women who are looking for sperm donors, as well as a sperm bank manager. Dawkins also explains kin selection and selfish genes.

Political humorist and author Bill Maher travels around the globe interviewing people about God and religion. Known for his analytical skills, wit and commitment to never pulling a punch, Maher brings his characteristic honesty to an unusual spiritual journey.
Muslims, Jews and Christians of many kinds pass before his jaundiced eye. He goes to a Creationist Museum in Kentucky, which shows that dinosaurs and people lived at the same time 5000 years ago. Maher speaks to a rabbi in league with Holocaust deniers. He talks to a Muslim musician who preaches hatred of Jews. Maher finds the unlikeliest of believers and, in a certain Vatican priest, he even finds an unlikely skeptic.