“The Atheist Bus Campaign began when Ariane Sherine wrote an article in June 2008 about Christian adverts running on London buses. These ads featured the URL of a website which said non–Christians would burn in hell for all eternity. Ariane suggested that atheists reading her article could each donate £5 to fund a reassuring counter–advert.”
Update: Christian religious groups are about to respond with ads stating that “there definitely is a god”.