When in history did atheism become the only choice?

[BZ_Zorro]

Any thinking, rational person of today has to admit that in the year 2005, God is an absurb hypothesis. Science has progressed to the point where we can safely say the universe functions just fine without any divine intervention, and everything that exists/has ever existed can be explained sufficiently by naturalism. Where things haven't been explained, it is fairly obvious to an open minded person that 'God did it' is one of the most childish and least useful explanations we can come up with. And wrong on so many levels.

But 1000 years ago, we didn't have answers to a lot of simple questions. For example:

1. What are the sun and the stars?
2. Where did people come from?
3. How can we think and feel?
4. What is the world made of?
5. How did everything get here, all the elements, all the amazing diversity of life
6. What makes life tick? How is life different to non life? What is the life force that drives us?
7. Where does morality come from?
8. What happens when we die?

Looking at these questions, it's fairly easy to see (I think) how an uneducated but otherwise intelligent and thoughtful person could believe in God. There's simply no other explanation for the amazing world as perceived by someone from that era.

So my question is, at what point could intelligent people begin to infer that God is just made up? What breakthroughs made it possible? Or have there always been atheists who didn't have the answers, but suspected the 'all powerful Superdaddy/Sky Fairy' theory wasn't it?