If the objective was to undermine people's belief in God, then turning the atheist buses loose in Britain was largely a waste of time, because most British people don't believe in God anyway.

The atheist buses are all over London and some other big British cities by now, with a large ad running down the sides saying: "There is probably no God. Now stop worrying and enjoy your life."

But you have to ask: if the sponsors of the ad, the British Humanist Society, felt strongly enough about it to spend £35,000 ($50,000) to put the signs on all those buses, why did they only say "PROBABLY no God"?

It's not their fault. Tim Bleakley, managing director for sales and marketing at CBS Outdoor in London, which handles advertising for the bus system, explained that advertisements saying flatly that there is no God "would have been misleading" for religious people. "So as not to fall foul of the code, you have to acknowledge that there is a grey area."

When the complaints rolled in anyway, alleging that the ad was offensive to Christians and that the "no God" claim could not be substantiated, the Advertising Standards Authority ruled that the ads were "an expression of the advertiser's opinion and that the claims in it were not capable of objective substantiation". For a non-theological organisation, the ASA is pretty sharp.

Never mind all that. The real question is: what did the British Humanist Society think it would achieve with its ad campaign? It's not as though non-believers in Britain were an oppressed minority. In fact, they're not a minority at all. They are the majority, although you have to read the statistics carefully to realize that.

According to the 2001 census, only 7 million people in Britain said they had no religion, while 37 million said they were Christian. As well, 1.5 million were Muslim, half a million were Hindu, 390,000 were Jedi Knights (there was a conspiracy among younger Britons to mock the process by claiming allegiance to the religion of Star Wars), 329,000 were Sikhs, and 260,000 were Jewish.

Those numbers suggest that Britain is an overwhelmingly Christian country, with under 20 percent of the population non-believers. Yet three-quarters of the people in Britain do not go to church even once a year. On an average Sunday only six percent of the population is in church, and that figure has been dropping at two percent per decade since the 1970s. Something doesn't add up here.

When the International Social Survey Program conducted a more in-depth study of religious belief almost 20 years ago (1991 and 1993), it asked people if they agreed or disagreed with the statement, "I know God exists and I have no doubts about it". In Britain, only 23.8 percent of people said they agreed.

That's a normal number for Europe. In that ISSP poll, most European countries only registered between 20 and 30 percent for confident belief in God, although Italy struggled up to 51 percent, Ireland reached 58 percent, and Poland got the prize with 66 percent believers.

What is happening is that people in Britain and many other countries are answering the census question about religion in terms of their cultural heritage (which is, in most cases, Christian), not of their actual beliefs. It all depends on how you phrase the question, but the official figures are misleading. Actual levels of religious belief in Europe are very low.

Moreover, the collapse in belief is continuing, with the youngest least likely to identify with a religion. A MORI poll commissioned by the British Library in 2007 found that nearly half of teenagers in Britain were atheists.

This fits in better with what you actually observe from day to day in most European countries. People are no less moral than they ever were, but religion is simply absent in daily life in Europe, at least compared to the United States, where it seems omnipresent. Yet here's a strange thing: the very first place those bus ads came out was the United States.

The idea started in Britain, but the American Humanists moved faster. Their ads appeared on buses in Washington, DC, in November 2008, saying "Why believe in a god? Just be good for goodness' sake"—and there was little public outcry. Maybe the United States is not that different after all.

The United States, we are constantly told, has a level of religious belief almost as high as Iran's, and every Gallup poll since 1944 has reported that at least 94 percent of Americans "believe in God or a universal spirit". But look at that question. If you had any lingering guilt at all about having abandoned your ancestral religion, you'd say yes to that, wouldn't you?

When the ISSP asked its much more rigorous question, only 66 percent of Americans agreed with the statement, "I know God exists and I have no doubts about it". That was almost twenty years ago, and it's very likely that the level of belief has fallen since.

The United States is not the same as Europe, but it is not invulnerable to the same trends—which may be why President Obama, while rhyming off the roll-call of America's religions in the time-honoured fashion in his election-night acceptance speech, for the first time added "and non-believers".

Gwynne Dyer's new book, Climate Wars, was published recently in Canada by Random House.