I'm a Heterosexual male Atheist. I think Homosexuality is un-natural, and in the case of men, pretty gross.
That being said, people are free to choose, and I don't treat them any differently for it. Except:
I do not support gay adoption, and I think adoption should be a very-last-resort for straight couples.
As for AIDS, that comes with sleeping around, something which I don't think is sensible at all. I personally find that condoms ruin sex, so if the girl's on the pill and you haven't slept around - you can get away with it.