Heh, this is an interesting argument.
I'm going to kind of break it down from what I understand:
Religion: God hates gays
The Bible, as translated from the original Hebrew, actually doesn't really mention homosexuality specifically. That's more of a loose interpretation: it could also mean "temple prostitutes" or other similar things, which would actually make more sense, since at the time where Christian and Pagan beliefs were merging (when the Bible was 'written'), temple prostitutes were fairly normal for Pagan religions.
Also, anyone who counts homosexuality as a unholy sin of the flesh also has to remember that sex before marriage and sex after divorce were both stressed even more as sins of the flesh. Sins are not "worse" because less people act upon them. We are all sinners in that regard; get off the high horse and look on your own actions, I say.
Gays might hit on me
A lot of people are afraid that a gay person might try to feel them up or something, which I think is pretty major BS. Just because a person is gay doesn't mean they will try to grope anyone of the same sex; they like certain people just like straight people have preferences. That's just plain ignorance, no excuse.
They're going to try to get married (screw up existing, traditional systems)
Well, that's all fine and dandy that you feel that way, but there are legal ways to get the same rights that don't involve Christian marriages. The thing about most politics anymore is that people have the RIGHT to equality; that doesn't mean just when we feel like it's "correct" or "normal." Gays have the right to equal political standing, even when it comes to legal partnerships, and if you don't want to give them the religious side...well, that's up to the religion. However, legally, we are not permitted to be so picky.