What about being pure?

I've recently been thinking about this a lot more than I usually do, examining my life and my beliefs as i usually do. Where did we go wrong where did we go right, how far is too far, and why we are righteous or not. Are people who consider themselves religious or righteous denying themselves something by forcing people to feal guilty or has our society twisted what a relationship should be to the point where it is an abomination. I lost the will to follow the teachings of the bible just because somebody told me to a long time ago, and if you still follow some belief just because that was the way you raised, is just foolish. Instead challenge what you know or what you have been told to either prove it wrong or make that belief stronger. So now, why be pure? What is gained and lost from being pure or not. If you get instant gratifacation from haveing sex or masturbating why not do it all the time, why not do it in the street, why not do it whenever you feel like. What fullfillment comes from it. What is beneficial besides the instant gradifacation. If you can honostly look at where the sex has been taken it to in it's extreams, such as beastiality and snuff films and torture and other demented uses in which sex has been dragged through, and still think that there isn't a darkness there, then I have to honostly say that you are souless. Even looking at regular porn it doesn't seem to be right. But if we reduce sex to it's most wholesome and purest form, what is it? Does marrage in our society work any more. And if it does for who and why. I find to look at anything objectively you have to take any situation and move towards infinity, see where it gets you and if it's bad then don't do it, if it's good, then do it. This is the rule by which i determine whether I should or shouldn't do something. So if in a relationship you have sex because you want it and you want the other person to give it to you, then that seems to be selfish. Move that towards infinity what do you get. You get rape, abuse and other distorted sexual fantasies. So move in the other direction. If you want sex because it is something that you share with someone, if sex is something that you hold so prescious that it takes all of your love and effort just to give it away to one peron, then what do you have. So why be pure?