Going all the way back to the original poster -
One of the great composers and musicians of all time was J. S. Bach. Johann wrote that everything he did was for the glory of God. A LOT of the musical themes that he used in cantatas and as a church organist were melodies that were being played at the time in the local beerhall (a true German, he saw nothing wrong with beer, as long as it was not in excess, that is the German culture).
Before being saved, I was into complex music (such as a lot of Bach and Mozart) and musical groups like Yes, Chicago, Santana, and the Moody Blues. For a time after being saved, God had me listening to only Christian music and His Word. I even threw out all my collection of secular music.
After a time, He has allowed me to go back to SOME of that music, but not all. I like most genres of music, except the ones that are focused on killing, negativity, gangsta, whinin', "cryin' in my beer," and the bubblegum pop music that tries to sneak negative garbage into my head.
Each person needs to listed prayerfully to God for direction. As an example, some people can take a single drink of an alcholic drink - others would become an alcoholic. (Of course, one thing even worse is a 5'1" preacher that weighs 290 lb preachin' about the evils of alcohol without realizing that EXCESS in ANYTHING is SINFUL!).
People have brought up musicians who play both sacred and secular music. Same thing - each person needs to seek God for their direction. As a musician, your music should be a testimony of God's power and grace. Also, we are to be witnesses for God out in the world, we are not to just hide with other like-minded folk inside our churches! But our testimony pretty well goes down the drain if we cannot be distinguished from the unsaved.
I had the priviledge once of going to Israel - at the time of the Feast of Tabernacles. During that time, I met Christians from over 100 countries. There were many different ways of expressing worship, most of which I had never seen before. That trip really helped me get over thinkin that my way was the only way. Praise God, we have people from many different backgrounds and traditions in my local church - helps us see what is essential Christianity and what is needed diversity. Even in our local association, we have a great variation in styles of worship and music for worship. I just want to be listening enough to God to know when it is time to move on to the next type of praise.
Jim