Is Atheism Rational?

What any individual knows is only a minute fraction of the aggregate of all human knowledge in the modern world.

What is collectively known today is only a minute fraction of all that can be known of the cosmos as a whole, and will be known in the future.

What can be known today is undoubtedly only a small fraction of all that is, but which cannot be known by the human mind. 

So, given the necessarily abysmal level ignorance of even the smartest and most knowledgeable human, how can anyone rationally claim to know there is no God?