Marriage is an institution created by the church, yes. However if gay marriage gets passed it will legally be a marriage.
You can think of it what you want though.
But the bible also says slaves are okay and you can marry your 10 year old cousin.
The actual quote you're thinking of is that a man should not lay with a man as he does a woman for it is an abomination. I already detailed why I think quoting that is out of context considering the book it comes from.
PS: Cowgirl: Would you mind editing your posts before you submit them? I have a hard time understanding what you mean a lot of the time.
ETA: Wanted to add that once again, you're welcome to your interpretation of the bible just as we are. You may very well be right, but I strongly believe otherwise as I'm sure you disagree with me. That's exactly why I added at my last post that the best bet is to just love one another and then let whatever God there is do the judgement. :)