Diarmaid MacCulloch's own life story makes him a symbol of a distinctive feature about Western Christianity - scepticism, a tendency to doubt which has transformed both Western culture and Christianity. In the final programme in the series, he asks where that change came from. He challenges the simplistic notion that faith in Christianity has steadily ebbed away before the relentless advance of science, reason and progress, and shows instead how the tide of faith perversely flows back in. Despite the attacks of Newton, Voltaire, the French Revolutionaries and Darwin, Christianity has shown a remarkable resilience. The greatest damage to Christianity was actually inflicted to its moral credibility by the two great wars of the 20th century and by its entanglement with Fascism and Nazism. And yet it is during crisis that the Church has rediscovered deep and enduring truths about itself, which may even be a clue to its future.

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.

Atheist and scientist Richard Dawkins visits England, America and Israel interveiwing prominant people of faith; Islamic, Hasidic Jews, and the new Christian sects popping up throughout the world, and expressing his view of the extent to which this fanaticism has degraded our civilisation, and will continue to degrade it. "The God Delusion" explores the unproven beliefs that are treated as factual by many religions and the extremes to which some followers have taken them. Dawkins opens the programme by describing the "would-be murderers ... who want to kill you and me, and themselves, because they're motivated by what they think is the highest ideal." Dawkins argues that "the process of non-thinking called faith" is not a way of understanding the world, but instead stands in fundamental opposition to modern science and the scientific method, and is divisive and dangerous.

Dawkins opines that the moral framework of religions is warped, and argues against the religious indoctrination of children. He discusses specifically the idea of religion seen as a virus in the sense of a meme. He begins by explaining how a child is genetically programmed to believe without questioning the word of authority figures, especially parents – the evolutionary imperative being that no child would survive by adopting a sceptical attitude towards everything their elders said. But this same imperative, he claims, leaves children open to infection by religion.

The youngest foot soldiers for the Lord are shown in their native environment in this documentary. Becky Fischer is a children's pastor who runs 'Kids on Fire,' a summer camp for evangelical Christian children in North Dakota. Fischer believes in the political and moral importance of a Christian presence in America, and uses her camp to reinforce the religious training most of her charges are already receiving at home (the majority of the campers are home-schooled by their parents).
Using video games, animated videos, and group activities to help put her message across, Fischer encourages the kids to pray for the President and his Supreme Court appointees while urging them to help 'take back America for Christ.' For the most part, the children seem reasonably ordinary beyond the fact they pray with uncommon fervour and sometimes speak in tongues.
Along with Fischer and her cohorts, Jesus Camp features interviews with Ted Haggard, an evangelist and advisor to George W. Bush, and Mike Papantonio, a Christian talk-show host who believes the right-wing slant of many Christian evangelists is taking the church into a dangerous direction.