Atheist bus campaign spreads the word of no God nationwide

Donations totalling more than £140,000 to fund adverts on 600 buses across UK as well as in London tube stations

Anyone who has spent a chilly half-hour waiting for a double-decker may already have doubted the existence of a deity. But for those who need further proof, a nationwide advertising campaign aimed at persuading more people to "come out" as atheists was launched today with the backing of some of Britain's most famous non-believers.

The principal slogan – "There's probably no God. Now stop worrying and enjoy your life" – can already be seen on four London bus routes, and now 200 bendy buses in London and 600 across the country are to carry the advert after a fundraising drive raised more than £140,000, exceeding the original target of £5,500.

The money will also pay for 1,000 advertisements on London Underground from next Monday and on a pair of giant LCD screens opposite Bond Street tube station, in Oxford Street. Organisers unveiled a set of quotes from public figures – including Albert Einstein, Douglas Adams and Katharine Hepburn – who have endorsed atheism, or at least expressed scepticism about a Creator. The words "That it will never come again is what makes life so sweet" are quoted from the poet Emily Dickinson.

At the launch in a heated marquee next to the Albert Memorial, the television comedy writer Ariane Sherine, creator of the campaign, said: "You wait ages for an atheist bus and then 800 come along at once. I hope they'll brighten people's days and make them smile on their way to work."

She suggested the campaign in a Guardian Comment is free blogpost last June, saying it would be a reassuring alternative to religious slogans threatening non-Christians with hell and damnation. At today's launch she said the sheer number of donations, which were still coming in, demonstrated the strength of feeling. "This is a great day for freedom of speech in Britain. I am very glad that we live in a country where people have the freedom to believe in whatever they want."

Joining Sherine were Richard Dawkins, author of The God Delusion, Hanne Stinson, from the British Humanist Association (BHA), the philosopher AC Grayling and Graham Linehan, who wrote Father Ted, Black Books and The IT Crowd. There were messages of support from the actor Stephen Fry and the writer Charlie Brooker.

According to the BHA, "huge numbers" of people in Britain have non-religious beliefs – between 30 and 40% of the population, with a higher figure, between 60 and 65%, in young people.

Hanne Stinson said: "We all, whether we have religious or non-religious beliefs, have a right to be heard, and no one particular set of beliefs has any more right to influence the public debate than any other. The message isn't aimed at people with religious beliefs – it's aimed at atheists and agnostics."

Most commentators recognised the slogan as a simple statement of non-religious belief and appreciated that it was designed to reassure people there was no reason to worry about being non-religious, she said. "People can lead a happy, enjoyable and rewarding life without religion."

Prior to the launch, Sherine was concerned that the posters would be banned from buses operated by Stagecoach, the second largest public transport company in the UK. Its co-founder Brian Souter is a member of the Church of Nazarene, an international evangelical Christian denomination.

A Stagecoach spokesman said all adverts on its buses were vetted before being published. "This particular advert is being carried on a number of bus operators' vehicles across the UK. We took advice from the Advertising Standards Authority in advance of publication and we have been advised the advert complies with the relevant guidelines and legislation."

The theology thinktank Theos welcomed the campaign, saying it was a "great way" to get people thinking about God. "The posters will encourage people to consider the most important question we will ever face in our lives. The slogan itself is a great discussion starter. Telling someone 'there's probably no God' is a bit like telling them they've probably remembered to lock their door. It creates the doubt that they might not have."

A statement from the Methodist Church thanked Dawkins for encouraging a "continued interest in God".

The success of the British initiative has inspired atheists around the world. The American Humanist Association launched a bus advertising campaign last November with the slogan, "Why believe in a god? Just be good for goodness' sake", appearing on the sides, rear and insides of Washington DC's 230 buses.

The subsequent news coverage generated mostly negative phone calls and emails, with the largest number going directly to the organisers. Hundreds of complaints were sent to Metro, the government body responsible for the city's buses and subways. The poster provoked two counter-campaigns by devout Christians.

From Monday, buses in Barcelona bearing a Spanish translation of the British slogan will hit the streets, to the consternation of the city's Catholic hierarchy, while Italy's Union of Atheist, Agnostics and Rationalists plans to roll out atheist buses.

Atheists in Australia have fared badly with their campaign. Attempts to place slogans such as "Atheism – sleep in on Sunday mornings" on buses were rejected by Australia's biggest outdoor advertising company, APN Outdoor.