Because it is sick and wrong. And so is anybody who supports it.
And before some ignorant idiot says I'm a homophobe, I'm not. Anybody that knows me knows I'm not afraid of shit. That's just another term the libbies used that too many of you wanna be right-wingers have adopted.
And if anybody needs a common sense answer, it's quite simple. It is unnatural. Same sex cannot reproduce, which is why we have sex organs anyways.
Duh.