Responding to the OP:
A very wise pastor I used to have spoke sometimes about the differences between being in the world, insulated from the world, and of the world. I'm less interested in listening to Christian music than I am in listening to music as a Christian. Same goes for what movies I watch, books I read, etc. It's far more important to me that what I do, I do as one who loves Christ and understands people living in the real world, here and now. I don't function well living in a Christian-y subculture where what we see, what we hear must have the Christian-approved stamp on it.
Also, talent--including musical talent--is a gift from God. I can still recognize that and appreciate it, even if the person with the gift has yet to come to know Christ. The talent, the gift, still has value.