I found this quite surprising, however, personally I found the bus adverts war between some Christians and Humanists rather silly anyway.
An advertisement campaign run by the Christian Party, declaring “There definitely is a God. So join the Christian Party and enjoy your life”, has not only topped the Advertising Standards Authority’s Top 10 of most complained about adverts in 2009, it is one of the most complained about non-broadcast adverts ever. The adverts were on the sides of buses, deliberately mirroring the British Humanist Association’s high-profile “Atheist Bus Campaign” from earlier in the same year.
Ekklesia have picked up on this also and they conclude:
The religion and society think-tank Ekklesia suggested last year that while encouraging people to think about their convictions concerning the meaning and purpose of life was a good thing, pro-god and anti-god propagandists might be better spending their money on benefiting people and planet, and on finding ways of working together across boundaries of faith and belief for human good.