My first reaction to this was negative. Advertising that there is no God strikes me as no less obnoxious than advertising that Jesus loves you or that the Rebbe will be back soon. On the other hand, religions do in fact advertise, so maybe it's better to provide atheistic ads to counterbalance them.
In any event, I always get a little thrill when I see an atheistic sentiment expressed in public. For all the popularity of Dawkins et al, reminders that not everybody in the world is religious are too rare.
