I believe that there are plenty of underground Christian bands that would stay afloat in the secular industry. The aspect that bothers me the most about secular music is that you don't know what the artists' religious beliefs are. All music is a ministry, and it is not always for Christ. Music is the door to the soul and you need to be careful what you let in. Many secular groups are into new age believes, and eastern religions like Buddhism and Hinduism.
Many groups sing about sexually immoral issues.
By listening to Christian groups not only are you supporting their ministry, but their lyrics are actually beneficial to you walk with Christ. Many people tell me that they only listen to these secular groups for the music, and they don't even listen to the words. By buying their music and merchandise, you are actually helping them spread their message of lies. The group Led Zeppelin is involved in the occult. Another thing that bothers me is when people claim that Christian bands copy the styles of secular artists.