Although Kevin DeYoung is not, as he admits, enamored with the (overused) word diversity, he argues in an intriguing post that it should be applied to the songs that we sing in church :
[T]he quest for musical diversity should not remove the particularity of a churchs worship. That is, its ok for Oakdale Community Church to be Oakdale Community, for First Baptist to be First Baptist, for worshipers in a remote Indian village to worship like, well, Indians. One of the problems with diversity as its sometimes construed is that it actually works against genuine diversity. Instead of people groups or churches enjoying their distinctiveness, they dabble (superficially usually) in every other culture. The result is that, in the name of diversity, every church or people ends up looking like the same multicultural experiment.
But let me hasten to add a final general comment. While it is wholly appropriate for a church to have a musical center, this does not mean we should only sing from that center. As I heard a speaker say recently, its fine (and inevitable) for a church to have a culture and tradition, but we must recognize that we have a culture lest we become enslaved to it. What I am arguing for is something in between the cutting edge and the status quo. On the one hand, churches need to sing familiar songs if the congregational singing is to be hearty and engaged. On the other hand, churches need to be pushed to learn new songs outside their center. As D.A. Carson puts it, The importance of intelligibility (in music, let us say) must therefore be juxtaposed with the responsibility to expand the limited horizons of one narrow tradition.
DeYoung proposes that churches incorporate four different categories of music: Psalms, hymns, contemporary songs, and non-anglo songs. Read the rest to see his explanation for each.