Is nihilism the logical extreme of atheism?

[genkaus]

So, basically, you are abandoning the varied wiki definition that was provided in the OP and coming up with your own?

The American Heritage Dictionary, Fourth addition.

This one?

ni·hil·ism
n.
1. Philosophy The doctrine that nothing actually exists or that existence or values are meaningless.

Yours was: Holding that all values are baseless and that nothing can be known or communicated.

The dictionary is just trying to be comprehensive - conveying ontological, existential and moral nihilism as distinct ideas in just one sentence.