This is by PZ Myers, author of the much read Pharyngula blog. Myers is an associate professor and biologist at the University of Minesota and writes frequently about issues to do with Evolution, Bible thumping creationists and the like. His blog is well worth a read if you haven't already found it.
He wrote this little creed in response to an infantile graphic that some Bible Thumper had created which supposedly illustrated the lot of the Atheist. It's worth reading the comments on that post. Like many of the commentators there I thought his little creed was worth reproducing. We are a fairly disparate bunch us Atheists but it does capture something of the common view shared by many Atheists;
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.