Having been a band wife since I met my husband..Well, band girlfriend, band fiancee and then band wife, I have been through a lot with my musician husband. We have had many conversations on what it means to be a Christian band or Christians in a band or if you need to talk during your shows to minister. Shaun Groves has a great post on this here.
The band Bobby is in now is a rock band. He loves it because he gets to play rock and roll. As the guitar player he doesn't have to talk all that much as the front man has to do most of the talking. Bobby is reading over my shoulder and ever point I wanted to make is out the window. He is not going to complain now he says. I think the point was that they are ministering the people they can without preaching at them. Shauns site says all of this far better than I can.