In any event, I can assure you that neither Jesus nor Paul nor John was suggesting that “sex was … always sinful.” Otherwise there would be no Theology of the Body.

The patristic record is mixed on sex and marriage. It’s at least arguable that Clement of Alexandria anticipated the Theology of the Body by some eighteen centuries. He had a refined appreciation for marriage and for the couple’s bodily union. I know that Chrysostom is sometimes cited in the negative column; but his nasty passages are almost all drawn from his pleas to a friend to return to the practice of celibacy — and I think his hyperbole is understandable, given the circumstance. Even Augustine didn’t say quite what you’re saying here — that sex is “always sinful … even if venially.” He did say that our practice of sex almost always involves some venial sin, but that’s a different statement altogether. My practice of phone conversation almost always involves some venial sin, but that doesn’t mean the phone is a bad thing.

Even so, we shouldn’t project Augustine (or Jerome!) back on the earlier Fathers. They’re writing with a far different set of concerns.