I don't hate God, as in, the entity that is in the Bible, I rather have a strong dislike in how it's percieved by the apparent majority of Christians. The Bible says - as far as I know - God is a loving and accepting entity, yet this apparent majority of Christians worship him in unnecessary volumes, as if they'd go to Hell if they don't pray fifty times a day. I know I'm exaggerating, but it gets my point across. I mean, if God really is such a loving and accepting entity, then He will grant me a good afterlife regardless of whether I believe in Him or not. It's about being a good person, not about believing in God. One can be a good person without being a Christian, and one can be a Christian, but still an ass.
An atheist doesn't have to hate God/gods. A misotheist hates God or the gods, and some atheists are misotheistic, some aren't. But not believing in gods doesn't mean you can't hate them, because if you don't believe then you see god as an idea, and you can hate the idea of gods.
I know atheists who hate the bad things that SOME theists do in the name of their God. I also know some less secure atheists who hate the idea of god and hate atheists, but you'll find assholes in any group.
How can someone hate something which doesn't exist for him? An atheist is someone who don't believe that a god exist so he can't hate or love or have other emotions for the god, because I think you can't have emotions for something that isn't there. But maybe there could be an atheist who thinks in a different way.... I don't know and I don't care if there is a god or not, I'm living my life whether there is one or not. That's my way to be an antheist ^^