atheism isn't exactly a religion
Christianity (in specific) and religion (in general) are "belief systems"
when something horrendous happens (like a hurricane killing thousands of people) Christians say "Satan did that" and when something "good" happens (like a hurricane hitting the beach with no loss of life) Christians say "God did that" or "it's a miracle"
most people need some sort of deity to help them cope with things like hurricanes
also the whole "heaven and hell" thing is just a coping mechanism for death, when a loved one dies, we say that they're "in heaven" and the idea of heaven helps us through what would otherwise be extremely traumatic, when someone is horrendously evil, we comfort ourselves with the idea that, after death, they will be punished for doing things that hurt others
atheism on the other hand
is living your life without the psychological crutch of deity and proccessing and dealing with reallity as it really is