While it is not necessarily an atheist bumper sticker, my all-time favorite was simply "CHOICE" - it covered all manner of subjects!
CHOICE was # 30 Buffalo BILLs. ..30 is journalism code for END OF STORY sent over wires...he was not famous for his jersey to be for sale
I believe today it would be equated with abortion. Have you seen it as a bumper sticker? I haven't (at least I don't think I have). Love bumper stickers though, especially the cars that have them as body paint.
The thing that I loved about such a simple statement was that it could be taken any number of ways. It could excite or anger anyone who might choose to interpret it in a manner personal to him/herself! It covers a multitude of 'sins', and I would love to have it again! The only sticker that I have is an oval with a picture of my dogs, my kennel name, and that "they'll drive you happy" (I'm a breeder) I used to have a Darwin fish, a Dogwin fish/dog, and a few other things, but only on the glass so I could remove if I so desired.
@Rustee the EQUAL SIGN " = " is quite powerful for gays and lesbians but the PEACE sign beats the xians mohammedans and other violent faiths..... taoist YINGyang I call my fraternal tadpoles but has not caught on like PAZ MNP et al