There has been a lot of discussion about professing Christian musicians that sing secular music and produce secular music. The reasoning behind this decision is, it's just a job.
It's not just a job, it's an expression of our love for God. At least, it should be. In everything that we do, we should do it for Jesus.
Matthew 10:32,33 (New International Version) says,
"Whoever acknowledges me before men, I will also acknowledge him before my Father in heaven. But whoever disowns me before men, I will disown him before my Father in heaven."
If we are too ashamed to say that Jesus is Lord of our life, because people won't buy our music, than He will disown us before the Father in heaven. It doesn't get any clearer than that.