Atheism is Indeed A Civil Rights Issue

This can be argued either way. Should you assume there is dessert? I don't think you should. This analogy isn't very good though since either outcome can be logically reasoned.

But my point is not that there is a dessert; rather that there is no correct default assumption that you can make. Atheism, a belief that there are no gods (as defined by the major dictionaries at least), also is an assumption, just like the belief that there is a God (or gods).