Modesty vs. Chastity

In "Mere Christianity," CS Lewis (unnecessarily) describes the difference between MODESTY and CHASTITY. I already knew the definitional difference, but Lewis' main point was that many self-proclaimed Christians confuse the two in practice, behaving modestly in public as a proxy for chastity, but really ignoring the latter in public.

As a rock-n-roller, I generally can't practice modesty in my live performances, and I don't think there is anything wrong with that, since chastity is really the goal of unmarried christians.

Some would say a lack of modesty encourages promiscuity, but that would be like saying heavy metal music encourages violence, and the courts have been quite decisive in saying there is no correlation. I think of titillating music as being more cathartic, allowing people to fulfill urges in a constructive way. Like killing people in video games, for example.