Casual sex is fundamentally selfish and degrading. Both partners agree to use and be used by the other. The message they send to each other, quite explicitly, is this: “I’m using you for your body, which I value only as a masturbatory object. You are a sex toy with a brain, but I don’t care about your brain and would rather you not use it right now.” . . .
In marriage, we give ourselves to the other, lifting them and ourselves up in the process. This is why sex ought to wait for marriage, because only after that lifelong oath has been sworn can we hope to use sex in a way that’s truly sacrificial and self-giving. Sex should be enjoyable, but it should also be an expression of love and devotion. If we take the love and devotion out of sex, we’ve turned it into an act of mutual objectification. And eventually, without the love and devotion, we won’t even have the enjoyment anymore.