At HAF we know that atheists are often happy ethical people just like anyone else. It is our goal to help dissolve negative stereotypes currently held towards atheists and facilitate productive dialogue with those of differing viewpoints.
"An Atheist loves himself and his fellow man instead of a god. An Atheist knows that heaven is something for which we should work now - here on earth - for all men together to enjoy. An Atheist thinks 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, and enjoy it. An Atheist thinks 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. Therefore, he seeks to know himself and his fellow man rather than to know a god. An Atheist knows that a hospital should be built instead of a church. An Atheist knows 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 knows that we cannot rely on a god nor channel action into prayer nor hope for an end to troubles in the hereafter. He knows that we are our brother's keeper and keepers of our lives; that we are responsible persons, that the job is here and the time is now." - Madalyn O'Hair
There is probably nothing more satisfying than being able to think about life's great questions without the restrictions created by religion and other superstitions. If someone inquires about your views, you have an answer. If you don't have an answer and are at fault, you can easily adjust your personal philosophy to better fit with reality. There are no imaginary chains.
Religiously minded people will often ask how someone can be happy without a belief in a god. Any atheist reading this can relate to how confusing that question can be. In our minds not believing in a god is like not believing in Santa. Thoughts of Santa filled many of our childhood minds with joy but we were only sad for few moments when we realized or found out Santa is not real. Religious views of god is just Santa for adults. Thoughts of god make many people happy, but that doesn't mean they would be forever sad if they found out god is imaginary.
We also find the question confusing because belief in god doesn't make everyone happy. It seems that for quite a few that belief just gives them a reason to carry on a life they don't like in hopes that when it is all over they'll be rewarded in another life. That's actually a very sad existence if you think about it...this life is not about this life but is about the next.
"But the happiness of an atheist is neither the vacuous enjoyment of a fool, nor the short-lived pleasure of a rogue. It is rather the expression of a disposition that has ceased to torture itself with foolish fancies, or perplex itself with useless beliefs." - Chapman Cohen
"When I finally came out of the closet and allowed myself the freedom of being an atheist, it was like a butterfly emerging from its chrysalis. I could read anything I wanted. Ask any questions I wanted. Challenge anything that didn't make sense to me. And after being the equivalent of a worker ant for so long, this was heady stuff indeed! I am still exhilarated by it. A chained intellect, as demanded by religion, is a pitiful thing. A free intellect is a thing to be treasured." - Judith Hayes
While many things cause joy for individuals, if there is anything specific to free thought that makes people happy it is what was described in the above quotes. The complete freedom to simply be the person you want to be without worrying about conforming to pre-packaged views is a lasting happiness.