Atheism is the lack of belief in a god or gods. Atheism is not the lack of a religion. There are many religions which do not have gods. Buddhism is one such.
How can it be proved that there is no god? Naturally, it cannot. If you think gods can be disproved, try to disprove the simpler idea that invisible angels push the planets around with their wings. If you can’t see them, and they produce effects identical to gravity, how can you prove that they are not there?
Humans have created countless gods. Gods are never disproved. They simply no longer have followers. Of course, there are still some gods left who do who have followers for instance YHWH, the god of the Christians and the Jews, and Allah, the god of the Muslims.
One common misconception
Atheism is not anger at a god or gods (this is called ‘apostasy’).
Negative connotations are associated with atheism by many people, thanks to widespread beliefs that atheists lack morals or a sense of personal mission due to their lack of belief in God.
Atheists are simply people who do not have a belief in god. Theists make sense of the world through a belief in god, and therefore the statement ‘I believe in God’ is a statement about them selves, not about reality. It means that at that moment in time, they find it useful to believe there is some sort of higher force which brings some sort of order to their lives that they think they cannot find on their own. When a believer no longer has need for a god, he or she stops believing.
Atheists only have a quarrel with people who claim that everybody should believe in god, because God is an objective fact which is supported by overwhelming evidence that the atheist is deliberately suppressing. This is not the case. There is no overwhelming evidence for god.