What is Atheism?

[Kernel Sohcahtoa]

I don't reject truths from other disciplines. I might not find a particular conclusion to be a truth. For example, while many people just accept evolution as truth (defines as the theory of common decent and the mechanisms by which that happens), [A] I don't make that leap because 1) it has not been proven and 2) my worldview gives more more possibilities than say, and atheist has. I'm not trying to start a debate on evolution, [B] just illustrating the difference in having to believe a theory is true and not having to believe a theory is true regardless of it's actual truth value. When they prove it, I will amend my belief.

There are plenty of secular members here on AF who don't leap to belief in god, because from their perspective, like the reasons given by you in [A], it has not been proven and their worldview provides them with more possibilities than a theist. Hence, regarding [A], is such a position a valid alternative to theism?
                                        
Also, regarding [B], there have been secular members on this site who have made similar remarks about their atheism, namely that if theists prove it (god), then they will amend their beliefs? Do you think that this is reasonable?  What are your thoughts?

P.S. I had a lot of formatting issues with this post, so I apologize for any inconvenience.