[Tribune7]

Why couldn't an atheist ponder it, realise that he or she is never really going to figure it out, and move on to other things?

Then atheism would be shallow and irrational. :-)

[Dimensio]

Then atheism would be shallow and irrational. :-)

No, atheism is a lack of belief in gods. "Shallow and irrational" are terms that might apply to individual atheists (actually, I've met a few to whom they do apply), but it is not a function of atheism in general.