I'm Japanese(-American) and thus have that perspective on it, more Japan than America.
Being non-religious means you simply aren't concerned. Are there gods? Great. Are there no gods? Awesome. Jesus is the one God? Okay. Zeus leads his pantheon of gods? Nice.
Atheism meanwhile is a deliberate belief in no religion. It's different from simply not caring about religion at all, because you do care about religion insofar as to not believe in it.
Implicit atheism is still concerned with not believing in religion.
The way I see atheism is that a belief in no religion is, by its nature, a religion. Joe is a christian and believes in Jesus, Bob is an atheist and believes no god; both are merely two sides of the same coin. You can't call yourself non-religious if you believe in a religion, whatever the specific form.
Being non-religious means you don't care; it's not that you don't believe, you simply could not care less one way or another. Wikipedia appears to call it apatheism[1] and more broadly irreligion[2], but semantics aren't the focal issue here.
Being non-religious means you simply aren't concerned. Are there gods? Great. Are there no gods? Awesome. Jesus is the one God? Okay. Zeus leads his pantheon of gods? Nice.
Atheism meanwhile is a deliberate belief in no religion. It's different from simply not caring about religion at all, because you do care about religion insofar as to not believe in it.