Atheism Is a Lack of Belief in Deities
Atheism is very individualistic. Whereas religions unify their members with a core set of beliefs and behaviors, atheists are united simply by a lack of belief in gods. This absence of a belief in gods can take many forms. Some atheists believe strongly that there is no god; others simply are not convinced that one exists. Other than that, atheists subscribe to a wide spectrum of ideologies and philosophies as they see fit.
The Atheist Movement
Atheists are one of the fastest growing minorities in the world, and many people are choosing to give voice to their views publicly rather than hiding their lack of religious beliefs from their communities. In some cases, this public declaration of atheism can lead to social backlash from friends and family; in other areas, it can even be physically dangerous to admit to atheism.
Members of the atheist rights movement might be interested in their right to raise children free of the influence of religion in schools. They may push for the safety and security of atheists in devoutly religious societies. Many nonbelievers are also part of other social activist movements devoted to the protection of human rights of many people, regardless of their beliefs.
All of this means that there is no singular, decisive "atheist movement."
There Is No Single Representative For All Atheists
The atheist movement has many faces, and each individual has the opportunity and the freedom to make a difference however he or she wishes. Just as godlessness can lead to different personal life philosophies that celebrate individualism and free thought, atheist movements’ strength comes from their diversity of opinions.
All of this means that there is no single representative of atheism or the atheist movement. No individual is doing it "right" or is somehow a "better" atheist than anyone else. There are no doctrines to follow and no mandatory beliefs to hold.
It's possible and even preferable to create cohesion without over-generalizing the traits of a group or forcing anyone to adhere to a definition that does not seem accurate. By celebrating the diversity of the atheist community, we have the freedom to pursue change and activism in our own way.