Person who does not believe in the existence of God:

A. Theist

B. Heretic

C. Atheist

D. Fanatic

Answer: Option C

Solution(By Examveda Team)

The one word substitution is Atheist.

Theist: Belief in the existence of a god or gods, specifically of a creator who intervenes in the universe.
Heretic: A person believing in or practicing religious heresy.
Fanatic: A person filled with excessive and single-minded zeal.
Atheist: A person who disbelieves or lacks belief in the existence of God or gods.