One of my best friends from college recently sent me this, written by his Episcopal church Rector. I love this; these are great insights into how a choir serves a congregation in worship. Here's a snippet:
"In worship, instead of allowing the choir to give us something, we invite the choir to sing in our stead. We invite these talented and faithful people to offer our prayers with their mouths, because they have skills for this kind of musical prayer that most of us do not. In other words, in worship, when the choir sings, we sing too, with our hearts and our minds if not with our lips."