PZ Myers eloquently encapsulates what I believe, so instead of trying to reinvent the wheel, I’m quoting him:
An atheist’s creed
I believe in time,
matter, and energy,
which make up the whole of the world.
I believe in reason, evidence and the human mind,
the only tools we have;
they are the product of natural forces
in a majestic but impersonal universe,
grander and richer than we can imagine,
a source of endless opportunities for discovery.
I believe in the power of doubt;
I do not seek out reassurances,
but embrace the question,
and strive to challenge my own beliefs.
I accept human mortality.
We have but one life,
brief and full of struggle,
leavened with love and community,
learning and exploration,
beauty and the creation of
new life, new art, and new ideas.
I rejoice in this life that I have,
and in the grandeur of a world that preceded me,
and an earth that will abide without me.