My point above about self-segregation didn't get a reply. It's not a conspiracy against Christian music. What happened was that evangelical/fundamentalist Christians have partially withdrawn from the mainstream culture. They think that mainstream music is too sexual, too violent, not dedicated to Jesus, etc., so they created their own music (and other entertainment) to meet their own special requirements. They also have their own schools, their own summer camps, and so on. In a way, it's an admirable do-it-yourself spirit. On the other hand, it can be a bubble, in which some people are getting a very distorted view of those outside of the evangelical/fundamentalist Christian subculture.
Your assumptions about Christian music couldn't be more incorrect. Just because you see Christians as living in a bubble doesn't mean that everything about life as a Christian is part of that bubble. I agree that there is a kind of social/cultural bubble in some Christian circles, and there are certain benefits and negatives that go along with that. However, saying that Christians invented some kind of new kind of music just to protect themselves of the "evils" of secular music is just plain incorrect and uninformed.
The contemporary syncretic Christian musical genre's origins can be dated all the way back to the inclusion of music in the early Roman Catholic Church. Composers like Palestrina, Gabrieli, and others wrote a
ton of music for church mass and special services. The composing techniques they tended to use were the styles accepted by the church, but many composers tried to gently push the envelope and toy with harmonies, forms, and ornamentations that were popular among secular styles of the day. The songs used in the early Protestant church were hymns, many of which were written by J.S. Bach with text by John Wesley. This style was descendent from the earlier progressive styles of the Catholic church.
Fast forward to the 20th century, where the Protestant church and hymns are considered to be traditional. In the '60s and '70s, the hippie movement was huge and had its own culture and music. The large-scale revival in California known as the "Jesus movement" reached a great number of these hippies who were, for all practical purposes, shunned by established society because of their "radical" lifestyle and disestablishment nature. Calvary Chapel is one of the churches that was created as an outreach to hippies. At first, Pastor Chuck Smith's church sang hymns (and still does, to this day), but members of his church and other churches wrote songs that sounded more like the secular music they were accustomed to. A fine example of this is the music of Malcolm & Alwyn (
), a popular Christian band from England in the 1970s whose rock style was heavily influenced by the Beatles. Their music was popular enough that they recorded a live album at Calvary Chapel Costa Mesa (the original Calvary Chapel church) in 1981. Phil Wickham gives tribute to M&A on Youtube performing a cover of their song, "Fool's Wisdom (
)".
Overall, the argument for Christian music being in an exclusionary bubble is untrue, especially contemporary Christian music which stemmed directly from popular rock styles of the 1970s. The people who believe that there needs to be a firm line defining Christian music and non-Christian music are generally those that don't fully understand music's role in the context of the history of the Christian church.