Marriage: violation of separation of Church and State?

For the past few weeks we've been reading Pride and Prejudice in English, the theme for this time being, obviously, marriage. We were having our regular class discussion and one of my classmates brought up the legal aspects of marriage, and another digressed farther by bringing up the sort-of recent overturning of gay-marriage in California. The rest of the class heartily engaged in the following argument of whether this act was wrong, and whether gay-marriage itself was right. I didn't participate, for the argument was long-exhausted and ridiculous to me. No one brought up the idea of whether marriage itself was right, as a legal institution, as I might assume that's what the LGBT community is fighting for- the legal benefits that their romantic interests indirectly exclude them from. I say indirectly because they're allowed to marry...just someone of the opposite gender. Not even a straight person is allowed to marry within gender. I just thought to myself that marriage is technically a business agreement, a legally binding contract between two people, but then there is the religious foundation. You, from my understanding, are bound to this other person spiritually in the eyes of "God", until death do you part (well, uh, theoretically, anyway). And most, if not all of the resistance to gay marriage came from the religious (about that phrase in the bible saying marriage is between chicks and dudes...well, the bible says A LOT of things, just pick out what works for you and ignore the rest), and this religious animosity, if I may call it that, was great enough to interfere with state affairs; namely the passing/overturning/creating/granting of the legal benefits/rights to those who don't want to be restricted to only the opposite gender, and wished to be legally bound to their same-gender darling. This is Church interfering with State affairs. Indirectly of course. I wonder if it a small part of the resistance was trying to stop the same gender couples as being on par with the "normal" couples.To be a couple like heterosexuals are couples. But that's not really not what I'm getting at. Marriage is alright, and anyone who wants to do because they think it'll make them happier, then great! Personally its something I'm not and never will be interested in. But Marriage should not be a legal institution. It is deeply entrenched in religious tradition and sentiment, it is a part of the church, and so should not also be a part of the state. And besides, why is the government involved in this area of our personal lives? What reason could it have to need to set laws and restrictions and this traditional form of romantic fulfillment? Why would anyone want the government and ugly legalities bound up in their most personal of relationships? It should not be a legal institution not only because the church has no place in the state- but the state has no place in the church! Marriage is wonderful as a religious institution, when you think of it as being spiritually bound to the one you love in the faith you hold equally dear. Having the government control who can and cannot be joining in holy matrimony has only brought about unnecessary grief and fustration for everyone, no matter what side they were on. We have a laisse-faire economy, wouldn't it be equally useful to apply the principle of "let the people do as they will" for our romantic and personal lives? Say to the state: butt out!