There are some people who still don't have any belief in their life. They are called "atheists", because an atheist doesn't believe in God. Basicly someone who embrace a religion based on religion of their family. Example: someone who was born in Muslim family or other religion, automaticly he / she would embrace Islam or other religion.
In the past, people usually followed religion of their king. In middle ages of Europe, recognized some words that “someone who govern some area, so he / she has a religion”. If their king moved to other religion, so a lot of people would follow religion of their king.
It is different with atheist who doesn't believe in God. In this case, not all atheists are the true atheists. In other case, atheist doesn't belief in God and life after dead. But their refuse death or afraid of dead.
A lot of atheists aren’t true atheis. They disappointed with their life. They think that God is their servant. When they asked something to God and God gave their other things which wass better than it. They think that God is not fair. They think like that, because they just think life in the world. It can cause someone not to choose a religion (atheist).
But, basicly choose a religion is freedom for everyone. So everyone free to choose a religion or not choose a religion. It caused a lot of religion in the world.