Not necessarily it isn't, I'm an atheist, and my atheism is not a contrary belief or claim, just a lack or absence of belief in any deity or deities. I would not hold a contrary belief or make a contrary claim unless the claim had been falsified, and the generic claim a deity exists is unfalsifiable. I must remain agnostic about all unfalsifiable claims, but also disbelieve them.
I've no idea what you mean by "it all happened by itself"? What are you claiming happened by itself?
No it isn't, but you seem to be denigrating faith now, which is irrational given you champion it elsewhere?
One alternative yes, if a god concept is unfalsifiable then I would of course disbelieve it, as I would any unfalsifiable claim, though I would also have to remain agnostic about such claims.
I am an atheist as I don't believe in any deity or deities, however I also remain agnostic about all unfalsifiable claims, including any god claims.
Since I am an atheist how else could I live my life?
No it isn't, as I simply don't believe in any deity or deities, though of course other atheists may and some do hold a contrary belief. Atheism however is the lack or absence of belief in any deity or deities, thus it encompasses both my lack of belief, and other's belief that no deity exists. This simple Venn diagram demonstrates it quite elegantly.