Does Atheism Lead to Nihilism?

[Angrboda]

Can one be a moral nihilist but not an existential nihilist?

I tend to flip those around and postulate a nihilistic approach to morals, but that existence itself is not, and cannot be, meaningless. (existential nihilism) Meaning, for me, is an a priori category which we find ourselves 'thrown into' by virtue of the nature of our minds.

Is that a consistent position? I'm not sure. It would seem existential meaning might ground ethical meaning. And I don't hang these beliefs on my theism, btw.