How can someone really be an atheist if they hate a God that they claim does not exist? Nobody hates Santa Claus or the Tooth Fairy.
Atheists tend to fall into several groups. Some don't believe in God but they have no hostility towards anyone who believes in anything.
Another group of atheists are those who hate God because they don't like how He runs his universe. Or because they know that God hates their sin and they love their sin.
Others are fools that act superior because they don't believe in God. Actually, among atheists, I prefer the arrogant, hateful, and condescending atheists because they make themselves and their beliefs unattractive.
RE: Why atheists seem/are so rude