First, I have to ask, what was the first song you played? I have to know what this potentially evil music could be!

I am not sure evil has edges hard enough to be defined, but for me, music can be unpleasant sounding, but I would call it reductionist to say music could be evil and good. Music is in some ways, what you project on to it, but it also can give you insight into another perspective. It is the beautiful harmony of souls, that of the artist, and of the listener, in the same way that is true of art and literature.

I would also point out the juxtaposition of some music and lyrics. Happy pretty sounding doesn't mean it is, surely that is something they should fear more, the loose morals and reckless living embodied in so much pop music...?

It is arguable the intention of the artist is the be all and end all, if a kid draws a picture, it is of what ever they say it is, regardless of what it actually looks like.

The never ending quest to understand the subjective, I mean, people can actually hear music differently, different parts of the brain are trigger by different music in different people, so in some ways they could hear evil. What ever that means to them.

Sorry for the somewhat over enthused far too long comment :)