I thought that the following definition of atheism was eloquent and covers all of the bases fairly well. It sure doesn't make us out to be the vile, morally degenerate, scheming, anti-American parasites that you always thought we were, right? :)
American Atheists -- Atheism
“Your petitioners are Atheists and they define their beliefs as follows. An Atheist loves his fellow man instead of god. An Atheist believes that heaven is something for which we should work now – here on earth for all men together to enjoy.
An Atheist believes that he can get no help through prayer but that he must find in himself the inner conviction, and strength to meet life, to grapple with it, to subdue it and enjoy it.
An Atheist believes that only in a knowledge of himself and a knowledge of his fellow man can he find the understanding that will help to a life of fulfillment.
He seeks to know himself and his fellow man rather than to know a god. An Atheist believes that a hospital should be built instead of a church. An Atheist believes that a deed must be done instead of a prayer said. An Atheist strives for involvement in life and not escape into death. He wants disease conquered, poverty vanquished, war eliminated. He wants man to understand and love man.
He wants an ethical way of life. He believes that we cannot rely on a god or channel action into prayer nor hope for an end of troubles in a hereafter.
He believes that we are our brother's keepers; and are keepers of our own lives; that we are responsible persons and the job is here and the time is now.”