London - For many Londoners, queuing for a tardy red double- decker bus may on occasions have prompted the utterance of a swear word or raised doubts about the existence of a deity altogether. From this week, those with lingering doubts will have their views confirmed in an atheist advertising campaign rolled out on 200 of London's iconic buses, the Underground (tube) network and transport systems in other major cities.
"There's probably no God. Now stop worrying and enjoy your life," is the principal slogan of the campaign.
It is the brainchild of a television comedy writer and is backed by the British Humanist Association (BHA), as well as prominent atheist Professor Richard Dawkins, the author of The God Delusion.
Posters featuring quotations from prominent figures known to have endorsed atheism - such as Albert Einstein, Douglas Adams and Katharine Hepburn - are to be placed on London Underground stations.
The words "That it will never come again is what makes life so sweet" are quoted from the poet Emily Dickinson.
TV comedy writer Ariane Sherine said her idea for an atheist publicity campaign was born out of anger at a Christian advertising campaign on London buses this summer.
Those who followed the "Jesus Said" campaign to its website were told that non-Christians "will be condemned to everlasting separation from God and then you spend all eternity in torment in hell."
Sherine said she believed that a lot of people had been outraged by the evangelical advertisements, without knowing what to do about it.
"Our rational slogan will hopefully reassure anyone who has been scared by this kind of evangelism," she said on launching the atheist campaign.
"I hope they'll brighten people's days and make them smile on their way to work."
Sherine said support for a fund-rasing drive to finance the adverts had exceeded all expectations, with donations totalling 140,000 pounds (210,000 dollars), as opposed to the original target of 5,500 pounds.
As the campaign starts rolling, there is every indication that it could go global, Sherine wrote in the Guardian newspaper.
In Spain, the Union of Atheists and Freethinkers has launched buses with a translation of the slogan in the northern city of Barcelona, and Italy's Union of Atheists, Agnostics and Rationalists was also planning to roll out atheist buses.
In the US, the American Humanist Association had been inspired to run a similar campaign on buses in Washington, but in Australia, a bus advertising scheme by the Atheist Foundation had been rejected by the country's biggest outdoor advertising company.
In Britain, where the BHA says up to 40 per cent of the population have "non-religious beliefs," the atheist poster campaign has met with a measured response from church leaders.
"We would defend the right of any group representing a religious or philosophical position to be able to promote that view through appropriate channels," said a spokesman for the mainstream Church of England.
"However, Christian belief is not about worrying or not enjoying life," he added.
The Methodist Church welcomed the atheist bus campaign as "an opportunity to talk about the deepest questions in life."
It could open up a dialogue between Christians and atheists which would "allow misconceptions to be challenged," said the Methodist church.
Professor Dawkins, however, said he would have preferred the main slogan to read: "There's certainly no God" instead of: "There's probably no God."
