The meanings of the words atheist and agnostic have blurred a bit. Technically I am agnostic since I say there would be no way to know, but many people think agnostic means "err I dunno what I think really" which isn't quite the same thing
So I say atheist instead.
My position being that there is no reason whatsoever to suppose that god does exist. Not that the evidence is inconclusive, but that there is none at all.
There is exactly the same amount of evidence that god exists as there is for the notion that rabbits rule the universe. We don't go around being nice to rabbits 'just in case' do we? That would be silly.
As for atheists believing in africa or anything they haven't seen. I do NOT believe in africa at all in the way people seem to mean.
The existence of Africa (or the duck billed platypus) is a claim that currently has a high probability based on a number of bits of evidence.
If someone tells me they have a duck in their pocket then whether I accept that as likely to be true is based on things like "do they normally lie? Is their pocket big enough to hold a duck? if there was a duck shouldn't I hear it quacking? and so on. I have no 'beliefs' in the sense that religious people have at all. It's all probability based on actual experience. This also means that should I turn out to be incorrect about the duck I won't suffer a crisis of faith and take to my bed. It's also how science works and so far science is winning since your VCR really does play back films, but prayers have no effect at all.
On the other hand religion is where you go "oh perhaps that stranger has a duck in his pocket that rules the universe.... Oh it must be true!.... Respect my belief everyone!"