When I spoke to some Christian organ scholars from Cambridge last June, one of their main questions was what to do when asked to provide music for heresy.
Many of us don't have to face this issue very often, as in God's grace we are working in churches where the pastor wants his congregation to sing truth. Every now and then, when we come across a line in a song with which we disagree, we can simply omit to sing that line, and then write a gracious note to the pastor about the concern. However, some of us sing in choral societies where we are asked to sing things with which we are uncomfortable.
Then there are Christian professional musicians like the organ scholars mentioned above, who are paid to play or sing in churches which have no concern for truth. And then there are Christian opera singers who are sometimes asked to sing things that are plainly evil.
