I can see how someone could be agnostic in their view. "I don't know, maybe there is, maybe there isn't. Who knows, who cares?" Yes. I can certainly see that, because I have been there. Thinking that perhaps "God" is just a spiritual Santa Claus for people who are afraid of death, etc....
But atheism? That is harder to grasp.
In order to be a true athiest, you would essentially have to know absolutely everything about everything. To be agnostic, you merely have to admit that you just really don't know.
Example: To say there is no gold in China, you would have to know absolutely every thing there is to know about China. You would have to know what is in every speck of soil in China, you would have to know whether there is gold in any of the homes in China, you would have to know if there are any gold teeth in the people's dental work in China, and so on and so forth. BUT: to say there IS gold in China, all you have to know is ONE person with a gold filling. One store with a gold chain.
The same would be with the existence of God. In order to say there is no God, you would have to possess absolute knowledge of everything in the universe and beyond.
At least that is how it seems to me. I don't know how my eyes do all the amazing things that they do. No one has been able to "build" a perfect substitute for the eye. If you lose an eye, you will never have the same vision again. To think it is the developement of a cosmic burp, doesn't seem very realistic. Something that magnificent had to have a creator. Don't you think?