Sentence:  And then the Amen corner took hold , re-enacting a form of group participation in worship that stemmed from years before the <WSD>Greek</WSD> chorus , spreading down through the African forest , overseas to the West Indies , and then here in Alabama . 
Meaning of the word marked with <WSD> tags:  a company of actors who comment (by speaking or singing in unison) on the action in a classical Greek play