I strongly oppose, based on religious, scientific and philosophical arguments.
The first is obvious, since I was raised Catholic.
Second, you can run a simple experiment. Take random pairs of living creatures, give them a hotel room to go screw, and observe how many pregnancies result after a large number of trials. You have probably already inferred from observations that two opposite sex humans, regardless of race, are capable. Similarly, a beagle can procreate with a poodle of the opposite sex. However, a same sex pair or the girl crazy enough to test riding a horse the wrong way will result in absolutely zero kids. From this experiment, you can conclude that a penis was meant to be paired with a vagina and, moreover, within a species.
Lastly, I like to commonly say people are getting so open-minded that their brains are starting to fall out. The words freedom and right are exaggerated. Many have started to notice the sense of entitlement growing in the minds of the younger generation, and it's not a side effect of the steroids put in the animals we eat. The more the rubber band gets stretched, the easier it will be to stretch until it breaks. Many have already made they point, if homosexuals want marriage then why can't the others have their desired polygamy? We've become a society like little kids crying when we see somebody else with something we don't have. The next time you're about to start complaining about the way something is, think about the reasoning behind why it is how it is. Occam's razor comes in handy. This is how you determine what is or is not meant to be changed.