I reckon at some point in time somebody already whacked the head over the dead horse on this topic but this is something I don’t really have a good answer to.
I work in a pretty scientific environment and I have to debate with people who have no bearing in faith. I usually have no problem getting the upper hand on occasion with debates on abortion. You can argue on developmental milestones, DNA, and appealing to a solid base of morality that most people have. Even the most militant atheist will admit that there is something fundamentally wrong with punching a pregnant woman in the stomach.
But gay marriage is a whole different animal, and outside of arguments that reference a divine creator and scripture, I haven’t found any argument that could hold much water scientifically and even ethically that sounded convincing enough to support a governmental ban on gay marriage. Any thoughts?