What are some of the clics of religious music--that a purely vocal--and have a cavernous-cathedral sound?

Try The Tallis Scholars sing Thomas Tallis(Gimell) .Tallis lived and successfully composed through the English Reformation and his work has an interesting variation in styles.The highpoint being Spem in Allium, 40 voices singing a short bible text in very rich polyphony.Try Allegri's Miserere (loads of recordings).There is a vocal arrangement of Barber's Adagio for strings titled Agnus Dei you might like. You could also try recordings of Pastrina.