Atheism is not a defining term; it represents the negation of a thing, not a thing in itself. It is a definition based upon doubt, and as such is inherently negative.
Imagine if you had to define yourself as an aunicornist, or an aflying-spaghetti-monsterist.
Don't define yourself by what you don't believe in, but by what you see and experience.
Atheism is a term better left unused, except in strict circumstances.