Besides accompanying congregational singing, probably the most utilized function of the church orchestra is to accompany anthems sung by the choir. The addition of orchestral instrumentation adds much color and interest to almost any choral performance.
I want to call your attention to our web page, "Orchestrations to Choral Works."
At the top of that page, if you click on the link in the blue box, you'll see a list of dozens of choral anthems I've orchestrated, some for full orchestra, and others for smaller accompanying groups.
It's been a blessing to have the opportunity to collaborate with a number of choral writers to create something to enhance the music they have composed. Here are a few examples for your listening pleasure:
FAITHFUL SERVANT (Cindy Berry) - Full Orchestra
A PSALM OF PRAISE (Benjamin Harlan) Brass and Percussion
CHRIST IS RISEN, HE IS RISEN INDEED (Keith Getty) "Celtic" ensemble
If you're looking for a hard-to-find orchestration, sometimes I may know of a source to recommend, even if it's not something I've written. I am also available to write what you may need on a commission basis, so please contact me if I can help you in any way!