Atheist (noun)

1. A person who believes that God does not exist.
2. A person who denies the existence of God or gods.

Origin:

Mid 16th century: from french athée or latin athaeus, from greek atheos "without god", from a- "without" + theos "god".

Examples:

1. He is an atheist and does not believe in God.
2. She is an atheist and does not believe in any gods.
3. Many famous scientists have been atheists.
4. He was raised in an atheist family.
5. The country has a large population of atheists.