Same-Sex Marriage.

... Sorry, yeah, I may be going into a bit of a rant here, just for a brief warning.

So, same sex marriage... WHY is it not allowed? What exactly is peoples problem with it?
Sorry if this is a bit out of the blue, but recently in England there's supposed to be a big vote or something about whether homosexual marriage should be allowed, and a lot of people are apparently saying it shouldn't be.
Now some people think same sex marriage is 'traditional' or whatever, and of course there's the religious views, but apart from that... What is wrong with it? Marriage isn't even that much of a religious thing, I mean its literal meaning is 'is a social union or legal contract between people called spouses that establishes rights and obligations between the spouses, between the spouses and their children, and between the spouses and their in-laws.' In short its just a contract binding two people together. Why should that not be allowed for same sex couples?
From purely the relationship side of this marriage is like the final step, its saying that you want to be with this person for the rest of your life, its tying you to one person. So I say it again: Why should that not be allowed for same sex couples? I mean when it all comes together, what is there really thats so wrong about it? I mean not allowed them marriage is in a way making them seem different from normal people, its not allowing them a simple civil right to be able to marry somebody they love man or woman, which in itself is basically a form of discrimination. And, well... In short, it just isn't fair.

Now looking at things from the religious point of view, I can sort of understand why Christians and such would not want same sex marriage. But marriage is NOT a religious thing, as stated before. I mean you don't have to get married in a church, it can still be marriage. However there are actually some gay/lesbian people who are christian, believe it or not. Also I don't really like preaching against peoples beliefs because I don't want to say what they believe is wrong, I myself come from a Christian family and I know people of various faiths. However there is one aspect of Christianity that bothers me the most...
Why is being gay sinful?
Why does God not love somebody just because they love someone of the same sex? Scientifically speaking its not unnatural, it can be seen throughout the animal kingdom in other species, but just looking at humans its not actually a choice. Say what you want but before anyone claims that it IS, I am bisexual myself and believe me its not a choice. Its part of who you are, and you can't just change it. But then apparently even if I live a completely sinless life, if I did go to Church and so forth, but remained gay, I would still go to hell. And if God didn't want me to be bisexual, then why am I this way? Like I said its not a choice, its who I am.
Now you could say well a lot of things that are sinful still exist even though they shouldn't, but most of those are things we can choose. Lust, sloth, greed ext are things we choose to do, however being homosexual is not a choice.

So... Yeah, sorry about my little rant, but I would like to hear what you guys have to say as well, get some other idea's in here