If you met physicians in internal medicine here in San Francisco, you might feel differently. It's not just a matter of AIDS and sexually transmitted diseases, but colo-rectal and other cancers, incidence of aneurysm, life expectancy and susceptibility to a number of conditions, let alone mental health. Of course, smoking and excessive drinking are also dangerous, but I can see why law makers are hesitant to call homosexuality "normal" and "natural." Again, I think this is ultimately the issue you're really trying to debate here, and you're acting like the worthiness of gay relationships is not even a question when--aside from people's religious persuasion--that is precisely the question. Legislators are required to protect the public good. You'll have to convince them that homosexuality qualifies, because I'm guessing most think it probably doesn't.
How is gay marriage treated in China and Russia? Those state governments have espoused atheism since their respective communist revolutions (which I think are despicable btw, but that's another topic).