Select the option that can be used as a one-word substitute for the given group of words.

One who does not believe in the existence of God.

Atheist

The one-word substitute for "one who does not believe in the existence of God" is atheist.

• Anarchist means someone who believes in the absence of government or organized authority.
• Egotist means someone who is excessively self-centered and has an exaggerated sense of their own importance.
• Cynic means someone who believes that people are motivated only by self-interest and that there is no such thing as genuine altruism.

Atheist means someone who does not believe in the existence of a god or any gods. It is the most appropriate word for the given group of words because it specifically refers to a lack of belief in God.