Personally I'd rather have the government out of marriage. Government reclassifies everything as a civil union, let private institutions marry those individuals who want a marriage in accordance with their institutional belief.
A homosexual relationship is totally hedonistic in its nature. Whether we believe it should be something higher with our intellect, our animal instincts tell us that same sex relations do nothing to propagate the species, do nothing to make the future a better place, and is ultimately a waste of resources.
Got nothing against them, there's plenty of people who are wasting resources these days.
Except they adopt children and give them loving homes to where they can actually make the future a better place and in the animal kingdom homosexual relationships are quite common.
So can girls. No gender and no sexual orientation is immune from getting STDs...and that's certainly not a valid reason to claim "gay sex is not natural".
Got nothing against them, there's plenty of people who are wasting resources these days.