Humanism: an outlook or system of thought concerned with human rather than divine or supernatural matters.
Atheism and humanism are different. Atheism (a-theism) is from the Greek, meaning "without god". Saying that someone is an atheist tells you nothing more than that someone isn't a believer. It tells you nothing about their values or behaviour.
For humanists, religion is an irrelevance. Throughout recorded history, there have always been people who've considered the human predicament without reference to supernaturalism, basing their decisions, actions and opinions on reason and experience. Humanism isn't equivalent to religion—a “lifestyle” for non-believers—and you don’t become a humanist by paying a subscription or simply saying that you are one. That’s too easy. How you think and behave is what matters. Humanists are curious, always ready to learn and to change their minds. They ask a lot of questions, including, “What would the world be like if everyone did as I do?”
There is no humanist creed, no set of beliefs to which every humanist has to subscribe. Humanism is not a dogma or a sect...as human beings we can find from our own resources the shared moral values which we need in order to live together, and the means to create meaningful and fulfilling lives for ourselves.