How far back do we need to go? 'Lord of the dance' is almost contemporary!

My local church choir (only 1 regular tenor, who'll remain nameless) can do any one of several oratorios. Possibly my favourite is:"Olivet To Calvary" By Maunder.
A simpler oratorio is Bach's "St Luke" passion. Whilst the music seems rather simplistic for Bach, and the attribution may be hotly argued. But for a choir looking for a straightforward introduction to oratorios, this is worth checking out.
I can also recommend John Stainer's "Crucifiction"

Nigel