It befuddles me that in this day an age, there are still people that don't know what an atheist is. I mean, I thought we were living in the information age? Aren't we the ones all over the news with our frivolous lawsuits and waging war on Christmas? Well, maybe that's some other atheists but that's not me. Anyway, here is a short summary of what an atheist is and isn't.
The prefix A basically means "not". Theist is defined as one who subscribes to the belief that there is a god. Put the two together and an atheist is one who does not believe in a god, or gods.
On a side note, when one is referring to a god in general, one uses a lower-case G. God with a capital G is a name. It is the name of the Judeo/Christian god, who claims to be the one and only. It also seems to be the name of choice for the ambiguous God of agnostics and deists.
Atheists do not share a common belief system or creed. They don't have worship meetings. Some have polticial meetings. Some don't.
Atheists do not worship the devil. The devil is a figure made up by men who needed a villian to make the whole God story work. If we worshipped the devil, then he'd be our god, and once again, atheist-no gods.
Atheists do have morals, or they don't. It's really an individual thing. One does not need a religion to be moral, and one is not moral simply because he is religious. Our source of morals are varied, from our own conscience, to our upbringing, to the collective conscience of society. An atheist uses logic and reason as a base for morals and ethics.
Atheists are not all mad at God. Some might be, but not all are. I'm not. I can't be mad at something I don't even believe in. I am somewhat pissed at some of God's followers though.
Atheists generally do not believe in the supernatural. But some atheists do believe in aliens or ghosts, and things of that nature. Or they leave open the possibility of the existence of such. Some are skeptical, and some are not. It's that simple. Atheists are as varied as the people that adhere to any other shared belief.