Atheism – a lack of belief/absence of belief in a god or gods
Theism – a belief in a god or gods
Atheist – a person who does not believe in gods
An atheist lacks belief in gods. This does not mean they believe gods do not exist. It just means they do not actively hold the belief that gods exist.
Theist – a person who believes in a god or gods
Examples of theists are Christians, Muslims and Hindus.