It's just knowledge that encourages the debate, not Atheism itself. Not believing in god does not have a purpose, it's just the way we're born.
Most, no, but it's import to a lot of children.
Atheism has a purpose?
Do you believe in the tooth fairy? If not, does not believing in the tooth fairy have a purpose?
Maybe there's a fairy that collects your hair when it falls out - do you believe in that? And in not, what purpose does not believing have?