Atheism, as a philosophical view, is the position that either affirms the nonexistence of gods or rejects theism. When defined more broadly, atheism is the absence of belief in deities alternatively called nontheism. Although atheists are commonly assumed to be irreligious, some religions, such as Buddhism, have been characterized as atheistic because of their lack of belief in a personal god.

Many self-described atheists are skeptical of all supernatural beings and cite a lack of empirical evidence for the existence of deities. Others argue for atheism on philosophical, social or historical grounds. Although many self-described atheists tend toward secular philosophies such as humanism and naturalism,there is no one ideology or set of behaviors to which all atheists adhere.

The term atheism originated as a pejorative epithet applied to any person or belief in conflict with established religion. With the spread of freethought, scientific skepticism, and criticism of religion, the term began to gather a more specific meaning and was sometimes used as a self-description by atheists.

Atheism is characterized by an absence of belief in the existence of gods. This absence of belief generally comes about either through deliberate choice, or from an inherent inability to believe religious teachings which seem literally incredible. It is not a lack of belief born out of simple ignorance of religious teachings.

Some atheists go beyond a mere absence of belief in gods: they actively believe that particular gods, or all gods, do not exist. Just lacking belief in Gods is often referred to as the "weak atheist" position; whereas believing that gods do not (or cannot) exist is known as "strong atheism."

The American Atheist Group has a definition as follows: Atheism is a doctrine that states that nothing exists but natural phenomena (matter), that thought is a property or function of matter, and that death irreversibly and totally terminates individual organic units. This definition means that there are no forces, phenomena, or entities which exist outside of or apart from physical nature, or which transcend nature, or are “super” natural, nor can there be. Humankind is on its own