Ask an Atheist

Belated answer and without reading most of the thread (just ignore me if it's already been said):

This is translated freely by me from an article in Hebrew, here.

Asking an atheist how he knows there is no god, is like asking him how he knows there is no polar bear standing behind him drinking orange juice through a straw. The answers to the two questions are similar: there is no reason for it to be there, and furthermore, the universe becomes far more complex and incomprehensible if it turns out that it is, in fact, there.