Singers sit in a square, all facing the middle. It's always a cappella. And it lacks, shall we say, the more complex subtleties of other religious/classical singing. Namely: dynamics do not exist. It is always as loud as possible.
Personally, I think this is pretty awesome! It looks like fun to sing, a style of music that's made for the joy of blasting out a killer harmony, and not necessarily made for joy of the listener.
There's actually a lot of opportunities to join in in Western MA. Maybe if I work up the nerve!