I am a Christian, and as far as I know, I've read through the Bible many times and I've never seen a single recorded instance of God saying married couples should be ashamed of sex and should only do it to procreate, and that enjoying it is a sin. He created sex, He is the one that made people's bodies the way they are. It would be silly if he thought enjoying it was a sin.
But we all know He created many laws around sex and how it should and shouldn't be done. The laws are meant for people's own good, as we all know sleeping around with 10 different people is bad for your health, and that studies show people who wait until marriage for sex are actually happier.
Waiting Works: Couples Who Wait Report 22% Happier Marriages (and Better Sex!) | WaitingTillMarriage.org
The why's shouldn't be too confusing. If you're looking for a happy relationship that you plan to make long term, or just the love of your life, you obviously shouldn't be giving them sex right away. I don't think they would feel very special if they got sex on the first day, and when they left, probably were thinking "Does he/she do that for every person they meet?"
Mark Gungor talks about this in his hilarious speech. It's two hours long, but well worth watching, even if you aren't a Christian and don't plan to be one.
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The Bible is not afraid of sex whatsoever. It talks about it in good ways and bad ways. Songs of Solomon is a very positive sexual book in the bible, and Ezekiel chapter 16 is full of gruesome stuff about it. The laws are meant to make sure people have sex the right way, with the right person - to ensure you have a better sex life.
If you don't want to watch the full two hour version, here's a shorter video straight to the point by Mark Gungor.
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