Is nihilism the logical extreme of atheism?

[Mudhammam]

The only way this argument can be considered logical if one can establish that god can one and only reason for life having objective meaning, purpose or value. A tall order, given that god hasn't even been established as a sufficient reason for those things.

Outside of intentional design in the internal structure of the physical Universe, which would seem to imply a mind somehow analogous to a human mind, and that has free will in the indeterminate sense and utilizes thought in bringing about a subsequent result through purposeful action, as in God, I can conceive of no other possibility for what might be considered objective meaning, purpose, or value. In this sense each agency of causation serves an objective purpose as each is like a necessary part in a large machine; however, it doesn't mean each part ever realizes the "ultimate purpose" of the machine, and it may not even be any more desirable than the "purpose" which the "nihilist" supposedly lacks.

Simply put, saying atheism leads to nihilism isn't sufficient - you have to explain which specific form of nihilism is supposed to the logical extreme of atheism. Then you have to explain why it is "logical" and not just an "extreme".

I think "atheism implies or necessitates existential nihilism" is a fair statement; as to whether or not God solves the existential problem is another matter (I can't see that it would, as we could always subsume the existence of God into the larger question of meaning or intention à la an infinite regress of "whys").