I'm a devout Christian and like good metal.
I'm a huge metal fan, as well as gothic music.
There are many Christian metal, gothic metal, and hard rock bands. I happen to listen to either (Christian or not).
Music, or TV or magazines or anything else for that matter, will influence those who would be influenced. We see again and again that kids brought up in a world of moral relativity and no sense of structure lose themselves. Left to their own devices they are easily influenced and brainwashed. Some are like the Columbine kids; a study in suburban neglect, and some end up like Jihad Johnny. Either way it's a nihilistic path you'll take when you have no where to go because you don't know where you are.