Keralys, do you live an a little tiny box? Have you ever met a functional gay family? I have met several, and I don't find them to be any different from my "normal" family.
I am, in fact, an extremely devout Christian. In my (note the stress on my) opinion, homosexuality is a sin and is morally wrong. However, I am not against gay marriage in the slightest. Our country was founded on the basis of religious freedom, and everyone in this country has the undeniable right to practice religion as he or she chooses. So, then, who are we to try to dictate them in what they may or may not do based on OUR beliefs? By shoving my beliefs down someone else's throat, what am I achieving other than making them think that all Christians are close-minded bigots?
I also beg to differ with your point that homosexuality has been shunned by every culture since the beginning of time. In the days of the ancient Romans and Greeks, women were seen only for reproductive purposes and men were sought out for "pleasure." I realise that this was not true for every Greek and Roman man, but it was a huge part of their culture at that time. Also, I feel that if it was not for the fact that men need women to reproduce and vice versa, it would not be considered morally wrong to be homosexual. The only reason that a man chooses to be with a woman is because he needs to have the ability to reproduce and that's how he gets it.