The evolutionary biologist and author of The God Delusion, who stepped down from his post at Oxford University last year, has subsidised the five-day camp in Somerset.

Camp-goers will be given lessons in rational scepticism, as well as sessions in moral philosophy and evolutionary biology.

There will be more familiar camp activities such as trekking, tug-of-war, canoeing and swimming but children will also be taught to disprove phenomena such as crop circles and telepathy.

The retreat is for children aged eight to 17 and will rival traditional faith-based breaks run by the Scouts and church groups. It will teach that religious belief and doctrines can prevent ethical and moral behaviour.

The camp is part of a campaign, backed by Dawkins and Professor AC Grayling, the philosopher and writer, designed to challenge Christian societies, collective worship and religious education.

Prof Dawkins said it was designed to “encourage children to think for themselves, sceptically and rationally”. All 24 places at the camp, which runs from July 27-31, have been taken.

Crispian Jago, an IT consultant, is hoping the experience will enrich his two children.

“I’m very keen on not indoctrinating them with religion or creeds,” he said. “I would rather equip them with the tools to learn how to think, not what to think.”

The emphasis on critical thinking is epitomised by a test called the Invisible Unicorn Challenge. Children will be told by camp leaders that the area around their tents is inhabited by two unicorns.

The activities of these creatures, of which there will be no physical evidence, will be regularly discussed by organisers, yet the children will be asked to prove that the unicorns do not exist.

Anyone who manages to prove this will win a £10 note – which features an image of Charles Darwin, the father of evolutionary theory – signed by Dawkins, a former professor of the public understanding of science at Oxford University.

“The unicorns are not necessarily a metaphor for God, they are to show kids that you can’t prove a negative,” said Samantha Stein, who is leading next month’s camp at the Mill on the Brue outdoor activity centre close to Bruton, Somerset.

“We are not trying to bash religion, but it encourages people to believe in a lot of things for which there is no evidence.”

A spokesman for the Church of England questioned Dawkins’ decision to stage a summer camp for atheists.

“We would defend the right for anyone to set up an event like this, as long as the young people are happy to attend,” he said.

“But in his imitation of the type of youth events that religious groups have been running for years, Dawkins makes atheism look even more like the thing he is rallying against.”