The notion that marriage = man + woman is the oldest notion of an institution in human history. Even the Spartans (who engaged in rampant homosexuality) never tried to change the definition of marriage. They revered and respected the tradition and institution because they realized it has a specific purpose for the Human Race. If gays had the same respect they would create a new institution to fit their selfish needs but we both know this has nothing to do with gays or civil rights or even marriage. The real target is the family unit.Marriage hasn't always been man + woman. Sometimes it was man + many women or man + slave or man + rape victim and then it was man + woman of the same race. Lots of things have been traditional. That doesn't make them right.
If gays want to have a ceremony and call it marriage and have their pretend marriages like roller coaster girl more power to them. Doesn't make it real marriage however. It never will be.If you can't identify any measurable harm caused by legalizing same-sex marriage, on what grounds should the government of the United States ban it?
We don't really know what the long term consequences are going to be to society. What we do know is that children do best when raised by their biological parents in a low conflict household. Depriving them that right to push a political agenda is wrong. Kids deserve their mom and dad.