Atheism is rejecting the belief in a God or gods.[1][2] It is the opposite of theism, which is the belief that at least one god exists. A person who rejects belief in gods is called an atheist. Adding an a, meaning "without", before the word theism results in atheism, or literally, "without theism".
Atheism is not the same as agnosticism: agnostics say that there is no way to know whether gods exist or not.[3] Being an agnostic does not have to mean a person rejects or believes in god. Some agnostics are theists, believing in god. The theologian Kierkegaard is an example. Other agnostics are atheists. Gnosticism refers to a claim of knowledge. A gnostic has sufficient knowledge to make a claim. Adding an a, meaning "without", before the word gnostic results in agnostic, or literally, "without knowledge".
While theism refers to belief in one or more gods, gnosticism refers to knowledge.[4] In practice, most people simply identify as a theist, atheist, or agnostic.