Hermes, thanks for the kind words. It’s an intriguing idea that the early Christians got their attitude about sex from the Roman Stoics. I’ll suggest to historians I know and see what they think.
As for casual sex, we may have to agree to disagree. Even when consensual it is still about using another human beings solely as a means to our ends, and here I think Kant (and the Stoics) got it right, that should be a no-no.
I understand your analogy with other transactions, but I don’t buy it. I don’t think of sex as mystical or sacred, but I think it is a sorry world one that equates such an intimate act between human beings with cutting hair.
By the way, I speak also from experience. I’ve done this a few times in my life, and it never made me feel good afterwards. By contrast, never had a problem whenever I went to the barber…