I think sometimes we get pretty legalistic about things. I think you can isolate yourself so much that you are not impacting the very people you are called to (the unsaved). That being said, so called "secular" music is full of Christian musicians making an impact on the un-saved. The band U2 would be considered "secular" by most but they reference the bible countless times in their songs and talk about Christian things. I mean Bono sings "You broke the bonds, Loosed the chains and Carried the cross, Of my shame, Of my shame
You know I believe it," That is as Christian as it gets. The difference is They are going to where the lost are and shining light. Van Morrison has many songs that would be considered "Christian" but he is considered a secular artist. Santana while most of there songs are secular in nature have songs like "Somewhere In Heaven" that speaks of Jesus dying so there is a place for us in heaven. These types of "secular" artists planted seeds in me that eventually broke down my barriers and opened me up to hearing the good news.
Yes, that's exactly the kind of thing I was thinking. This also makes God's grace available to those who shy away from the "church" scene and "Christian" distribution network. Some of these people, myself included, really want to know God, but something about a religious institution has been very painful or frightening. Well, the good news is that God isn't boxed in. He really does seek people out. He goes out in search of those who don't yet know him. I've really seen him do that through music.