C'mon, no biological explanations, please, only theological explanations will pass the smell test among some of our more right leaning members. In realty, sex is a pleasurable, activity. In the skewed reality in which we are supposedly headed (Christian theocracy), sex is a gift from God that only married believers may participate, otherwise it's a dirty, animalistic activity. Guess what, we ARE animals, simply more developed than others, therefore we have the need to participate in certain activities, whether or not a bible, torah or quaran says it's OK.
You have more dignity than that.
If that's true then there's no moral binding for any of us. Conscience is an illusion. Thankfully, neither is the case, and your statement is completely ridiculous.
However, the thought that sex should only be for reproduction is also ridiculous. It can indeed be for pleasure, but the Bible says it's only for married people to enjoy. Now if you don't believe that, that's your prerogative. It's not Christians' responsibility to enforce the moral standard, merely to make it known. God can do His own enforcing.