I’m no bible scholar so somebody correct me if I’m wrong.
The way I understand it, is if you have sex outside of marriage; that’s a sin.
My question is why?
Or more specificaly, why is it a sin to have sex with some one you DON’T love or have any kind of feelings for. (This providing both or all parties involved are conscenting adults. That haven’t been misled or misguided in any way in order to give sex.)
In traditional patrarchal societies, paternity is a big deal. It figures in to where you fit in to society, what you inheret, and what obligations you owe and are owed to others. A person without established paternity had few rights and is essentially left without a legitmate place in society. Most of the bibilical restrictions on sex stem from when Judaism was a tribal religion and were designed to keep things running smoothly and assure that everyone has an established paternity so that “he’s not my kid” and “I’m owed this inheretence, not my bastard brother” arguments didn’t take up everybody’s time and energy.
Which, I think, makes it perfectly clear that such restrictions need no longer apply. Our ideas about sex and marriage were formed in a time when, to find her husband, a wife needed only look out at the different parts of their farm. Society has changed, so social norms need to change. This has already happened in Europe. Premarital sex doesn’t scare people across the pond.
The Christian answer, as is my understanding, anyway:
Because God set it up that sex shouldn’t happen without the covenant of marriage.
Sex is a sign of that covenant, and only those that have entered into that covenant get to do it. All sex does is express outwardly the inward joining that has taken place – the couple has been spiritually united. Instead of God looking at me and seeing just Abbie, he sees Abbie and Mr. Carmichael, because to Him there’s no difference. We’re one.
The good news is that once the covenant is made, the happy couple can do whatever they want. All manner of freakiness is ok with God (as long as it’s just the two of you and you both agree), the book says the marriage bed cannot be made unclean.
There’s more going on than just the physical when people have sex – it’s creating spiritual bonds, too. Non-married couples are not spiritually united in God’s eyes, yet they are doing something that expresses that a covenant has taken place, even if it hasn’t. (What if they’re not Christians, you’re probably wondering. Well, assume for a minute that Jesus is who He says – that would mean that even though non-Christians aren’t in covenant with Him, they are still subject to the spiritual laws that God has established. Sure, they can choose not to acknowledge it, but they’re still subject to them. I can choose not to acknowledge that gravity exists, but if I drop an egg on the kitchen floor, I’m still going to have a mess.)
Sex is also a “picture,” if you will, of Christ and the Church. The Church is the bride, which Christ died for – just like husbands are supposed to willingly lay down their life for their wife if need be. Covenants are always made in blood in the Bible, right? Well, what (normally, but not always) happens when a woman loses her virginity? She bleeds. I’m getting in waaaaaaaay over my head because Biblical symbolism isn’t my forte, but my point is that just as it took blood to create the covenant because Jesus and the believer, it (figuratively speaking) takes blood to enter into the marriage covenant. I am NOT saying that there is no covenant if the wife isn’t a virgin when she gets married, or if she doesn’t bleed. I’m speaking figuratively here.
The womb is a symbol of the place where Jesus went after He was crucified – the holiest of holies. (The holiest of holies was, in the Old Testament, where God was when the Israelites build the tabernacle. NOBODY went in there, and it was separated by a veil. If you went in, you’d die. Now, because Jesus created a blood covenant, we get to go in too, and we don’t die. And we don’t need a tent to do it, either.)
The womb is where life is created. Just as we cannot approach God without Jesus there ought not to be approaching the womb without a covenant already in place.
It would be like an atheist getting baptized, if that makes sense. Baptism is something we do to show the world that we’ve given our heart to Jesus – it means something because something else (belief) has already taken place.
If the first part hasn’t taken place, you are not privileged to do the second part.
Now hopefully FriarTed will get in here and better explain what I’ve bungled and whatever I’ve left out.
The fallacy in your argument is the Christian god exists. Billions of people who believe in god on this planet disagree.
What part of “the Christian answer” did you not comprehend?
Shakes wanted to know, I told him.
Where in the bible is all that? 
Armed with the expertise that comes from having read several pop-science anthropology books, it appears to me that most, or all, cultures have strong restrictions on sexual activity, whether or not they are at all related to Judeo-Christian traditions. The Sambia, for instance, a Highland New Guinea tribe that was isolated from Western society until a couple hundred years ago, have all sorts of restrictions on sexuality (though they are far different from our own.) Sex is very dangerous, even within the bounds of marriage, in the Sambia tradition - contact with the breath of a woman during sex can potentially deplete a man’s masculinity or even kill him. Something like half of the year is ritualistically taboo for sexual activity for one reason or another. During his wife’s period, a man must undertake certain purification rituals. Oddly enough, these restrictions occur in the same culture that mandates a period of ritualized homosexuality during adolescence (thus limiting a boy’s sexuality during his most, uh, horny years to other boys.)
The point is that every culture I’m aware of has traditions to limit sexuality (and in fact, I can’t think of any that don’t practice some form of marriage.) Sexuality is an immensely strong drive, and I think there’s probably a universal tendency for societies to try to constrain that drive. It appears to me that early human societies must have developed these rules for a reason; apparently, unconstrained sexuality was bad for the tribe as a whole.
Sex makes babies. Babies are a lot of work for a long time, and doing it all yourself is hard. Since the best solution is for two or more people to get together and form a household which is responsible for maintaining those kids, the adults need to be able to stay together and cooperate for umpteen years without killing each other. Since sex is very powerful urge, society needs an equally powerful taboo to oppose it and channel it in the right direction.
The flaw in my theory is that gay sex should be a sacrament. 
::Rereads Excalibre’s post::
I’ll be a dill pickle. In some neighborhoods, it is a sacrament.
Well if you don’t beleive in “Him” … then you can get laid…
The 66 (or 72 if you’re Catholic) ancient scrolls collectively called “The Bible” are not the only source of Christian doctrine and moral teaching. Specially on the nature of the sacraments.
Damn . . . I thought that was a link.
What coffeecat said. Patriarchal societies’ obsession with paternity was always just a cultural mean to an end, and that end is controlling reproduction so it happens in a context where there are people dedicated to taking care of the baby so that the society in general doesn’t have to.
Marriage as institution, family as institution, the prohibition on sex outside of marriage, the traditional imperative to hold out for a fellow who can support you and your babies if you’re female, or to seek out stability, money and power as a prerequisite to becoming ‘eligible’ if you’re male, … it’s all about keeping a lid on reproduction.
It’s not that patriarchal societies wanted reproduction to be scarce and rare — far from it! If anything, the optimal result was to get the sex drive into an efficient harness, to give young strong energetic males a good reason to bust their butts working hard for the older men who ran the society instead of challenging the older men’s authority or spending all their time flirting with the females instead of working hard; and then as soon as they’ve established success, to get them married off and start making babies in large quantites. Hence the historical interference with and condemnation of birth control, and the advantages of it being difficult for women to do well as other than a man’s wife (and the wary suspicion of any that nevertheless manage to do so, e.g., witch-burnings). So patriarchy means institutionalized sex inequality, men possessing women as property, the doctrine of femme couvert, the sexual double standard, etc.
Because back when the bible was written, getting syphilis was a pretty nasty affair. The only way to cut down on that was to limit your sexual partners. Of course, that’s too complicated an explanation for the masses, and wouldn’t be likely to work. So you tell 'em that God says not to fool around until you’re married or you’ll go to hell. Problem solved - sort of.
Well, it wasn’t a lie-I imagine getting syphilis back in those days WAS the equal to Hell.
It’s in the middle somewhere 
IMO, the entire premise of the question is flawed: if we’re talking about Christianity, God does want you to get laid, and he wants it to be a mind-blowing earth-shaking jaw-dropping good experience.
Prserving sex for marriage is part of that. By keeping it in the context of a loving, committed, monogamous relationship, two people can experience something – a union, a relationship – that cannot be had otherwise.
The OP’s question, is, from the Christian God’s perspective, a bit like a child being taken to his favorite restaurant – but wanting to eat Twinkies in the car, and asking “Why don’t you want me to eat?”
Oh, and Abbie and furt have provided a pretty good summation of the major mainstream-christian theological justifications for the rule that sex is only to be in the context of marriage. Excalibre, AHunter3, coffeecat and blowero have, in turn, provided a pretty good summation of the anthropological/historic origins of restrictive sexual mores. So SHAKES got the original question plus a bonus.
And like Rashak said, if you want guilt-free commitment-free casual sex, you just need to change how you look at the world.