2. A person who has no belief in a God or Goddess. Just as a newborn has no concept of a deity, some adults also have no such belief. The term "Atheist" is derived from the Greek words "a" which means "without" and "Theos" which means "God." A person can be a non-Theist by simply lacking a belief in God without actively denying God's existence. This is the definition of Atheism used by many Atheists. They use the term "strong Atheist" to refer to a person who denies the existence of one or more deities.