An atheist worldview encourages relativism, with its insistence on removal of moral absolutes and rejection of truth claims. One of the finest expressions of self-defeating nature of relativism is the poem Creed, written in 1993 by English poet and music journalist Steve Turner. (The postscript, called Chance, was added later).
Personally, I prefer the Nicene.
Creed by Steve Turner
We believe in Marxfreudanddarwin
We believe everything is OK
as long as you don’t hurt anyone
to the best of your definition of hurt,
and to the best of your knowledge.
We believe in sex before, during, and
We believe in the therapy of sin.
We believe that adultery is fun.
We believe that sodomy’s OK.
We believe that taboos are taboo.