To MisakixMikasa and other who insist on comparing gay marriage to marrying animals or children, or cal it "the slippery slope", well..
We have reasons why we pass certain laws. We don't pass laws "just because". For example, you can't marry children because children do not have the mental development to understand what they are doing or to make decisions like this. You can't marry animals because animals are a lower life form and it would be considered cruelty. And you can't marry your sister or brother or daughter or son due to the serious genetic problems it would cause. You can't marry more than one person because the potential for fraud, monetary or otherwise, is present. All those represent serious harm to the public and individuals if we allowed them. In other words, we have reasons for laws about those things.
Being gay, on the other hand, is legal. There is no harm to the gay people or to the public. In other words, "because it upsets some of you" is not a good enough reason to have a law banning something, say gay marriage. Therefore, they should be able to do all the legal things the rest of us can do and they shouldn't be allowed to do the things in the above list we also aren't allowed to do. Very simple.