Often tells a story from the Bible or has a spiritual theme, but not always exclusively religious. Bach composed the oratorio 'St. Matthew Passion' which depicts the Passion of Christ.
Pro Tip 2/3
Concert Performance
Oratorios are meant for listening in a live performance. They are not staged like operas. I attended an oratorio and was moved by the powerful combination of choral and orchestral music.
Pro Tip 3/3
No Costumes
Unlike operas, performers in an oratorio don't wear costumes or act out the narrative. The vocalists stood in formal attire as they sang the oratorio.