When- The first individuals to identify themselves using the word "atheist" lived in the 18th century.

where-  atheism blossoms in places where most people feel economically secure, particularly in the social democracies of Europe, as there is less uncertainty about the future with extensive social safety nets and better health care resulting in a greater quality of life and higher life expectancy.

why- Academia states that in the absence of proof of the existence of something it must be deemed not to exist until verifiable proof is found thus god is held not to exist on some sort of verifiable evidence.

what- The rejection of belief  in the existence of deities.

-good things about is is that atheism is a reliance on the fact, which are things that exist. atheism lets someone live in the real world so that they give their time and energy to real poeple.

-freedom to think for yourself and not be judged because you view the situation differently.

- helps cope with the stresses of life and the inevitability of death.

-atheism gives a coherent mechanism by which to make sense of the senseless

2. It is celebrated more in the USA than Mexico.

3. It's mostly celebrated within the state of puebla.