This is a response to C. S. Lewis's defense of traditional sexual ethics by Keith Parsons.
It looks as if we certainly can, (pun intended) screw ourselves up with our sex behavior. It looks to me as if permanent happiness in relationships is found primarily in relationships in which fidelity is promised and that promise is kept. That won’t take you all the way to the traditional religious position, but it does make it incumbent on critics of traditional sexual morality to replace it with some kind of behavioral code that keeps our sexual conduct from causing harm.
You can cause harm with every other part of your life, and there are rules governing conduct in those other areas. Why should there be no rules in the sexual area?
It is one thing to criticize Christian sexual morality. It looks like a soft target. But even if you disagree with the traditional code, you have to show some understanding of the considerations that might have led religious believers to accept these kinds of restrictions on sex behavior in the first place.