"Religion is accustomed to getting a free ride - automatic tax breaks, unearned 'respect' and the right not to be 'offended', the right to brainwash children," Professor Dawkins said.

"Even on the buses, nobody thinks twice when they see a religious slogan plastered across the side. This campaign to put alternative slogans on London buses will make people think - and thinking is anathema to religion."

His outspoken comments are backed by BHA chief executive Hanne Stinson, who said the advert would be welcomed as a "breath of fresh air" by many.

"If it raises a smile as well as making people think, so much the better."

though being atheist, i am not sure that through nigation one passes ones saying.