Just to clarify a few things in this topic;
Agnosticism - The belief that it is impossible to know whether there is a god or not
Weak atheism - The lack of a belief in God
Strong atheism - The belief that there is no God
A person can be both atheist and agnostic, or both christian and agnostic. Atheism also doesn't technically require active belief (there is no God) it simply requires somebody to not believe in a God, which is passive.
Atheism is also in many ways seperate from religion (and certainly is not a religion in itself), a person can be atheist and religious at the same time - as most Buddhists and I think some Hindus are. Religion is a belief system with dogma and rituals, atheism simply doesn't have those.
Now, on topic: It's a sign of America becoming somewhat more secular and progressive in my opinion.
