Is nihilism the logical extreme of atheism?

[genkaus]

I think you're right that theism offers no viable solution but on what basis do you think an ideal could be called objective?nature.

There is no simple answer to this. We'd first have to define the terms and the context within which we are considering the question.

The problem is that no facts of nature actually confer universal principles of this sort beyond the ideals that human beings themselves espouse.

Facts of nature are not relevant here. We are talking about beliefs. Specifically, beliefs compatible with atheism which - if true - would confer objective meaning and purpose. Whether or not those beliefs are true is doesn't affect the answer.