Me too. Gay and opposed to gay marriage.
I know my reasons. What are yours, if I may?
I spent a day's worth of HN participation arguing against gay marriage, a few months back, and came out net positive in karma. If you're interested in those arguments, they begin here: https://news.ycombinator.com/item?id=12976422
Should you take the time, I'd be interested and obliged to hear any thoughts they occasion.