[Misterioso]

Religion=theism. No religion=atheism. Simple as that.

[GoDuke]

the·ism
[thee-iz-uhm]
noun
1.
the belief in one God as the creator and ruler of the universe, without rejection of revelation (distinguished from deism ).
2.
belief in the existence of a god or gods (opposed to atheism ).

So no, it’s not as simple as that.

[tanknetter]

Religion=theism. No religion=atheism. Simple as that.

True. "Atheism" has been misappropriated by atheists, who take an active belief - one they promote/proselytize just like any other religion - that there is no God.