Quote From: gcnjustinI'm still here... and thanks for the question!
Unfortunately, it would be pretty close to impossible to really get into the Bible issues in any deep fashion on a message board like this one. There's just too much to discuss. However, I'll give you a short answer and tell you where you can learn more.
Monogamous gay couples weren't a part of the culture in which the Bible was written, so the Bible doesn't take a position on them at all. We see the Bible condemning gang rape, idolatrous orgies, and the like, but no gay couples are mentioned at all. (There are some who believe that a few gay couples are mentioned in Scripture, but it's far from universally accepted.)
However, there are other passages that provide strong ammunition for the pro-gay-marriage argument. One example is Romans 13:8-10, which makes it clear that sin is *always* evidenced by a lack of love. Adultery, theft, murder... all of these are unloving actions. But there is nothing about a committed same-sex relationship to make it less loving than if one of the partners were of the opposite sex. Therefore, if we say that gender alone is the defining characteristic, you'd have to find a very clever way to work your way out of the very plain statement in Romans 13.
That's one of many examples. On my organization's website (gaychristian.net) we have several Bible-related resources that deal with these issues. If you want a very in-depth discussion of the issue from both sides, check out our "great debate" page, which goes into way more detail than you probably ever wanted. :)
I hope this helps! Incidentally, we also have some resources for moms who are struggling to come to terms with the coming out of their kids, as well as a bunch of other things. Check it out if you're interested.
God bless!
--Justin