Atheism is the opposite of theism. Atheism comes from the prefix a- which means no or without, the word theos meaning God and the suffix -ism which means ideology, worldview, idea, belief. A-the-ism is therefore the belief (-ism) that there is no (a-) God (theos). Atheism is the belief that there is no God.
A common argument is to redefine what Atheism means. It’s popular to claim that atheism means “a lack of belief in God”.
Doesn’t say anything about reality.
Saying you lack a belief in God doesn’t say anything about the objective reality outside your head. You lack a belief. So what? Who cares?
To the question “Does God exist?” there are only three possible answers:
- YES – You’re a theist, deist, pantheist etc.
- NO – You’re an atheist.
- I DON’T KNOW – You’re an agnostic.
Can be reversed
If an atheist doesn’t believe that there is no God, they just lack a belief in God, then a theist doesn’t believe that there is a God, they just lack a belief that all of existence came from nothing.