So. looking at this from a different perspective, if the definition of something is OPPRESSIVE, then that definition needs to be changed.
When Jefferson wrote the Declaration of Independence, remember, "All men are created equal" excluded blacks, because according to the definition at the time, blacks were not men. Somewhere along the line, that definition, fortunately got changed. It's time to change the (govenrnment's) definition of marriage then. Your religion can define it however the fuck they want. And so can mine.
Oh stop. "Oppressive?" No one is being oppressed. For one thing, making gay marriage legal is surely not going to change the majority of the population's opinion on the topic. It might even increase anti-gay sentiment. It might actually increase real oppression in this country.
Secondly, and hear me well: Being gay is not comprable to being a minority race because...at least for some people...there is an element of choice involved..
Have a nice day.