Crossword puzzle clue "it's done a lot in church"

It's done a lot in church

Source of the line "What's done is done"

"Done and done!"

"Done and done"

"The Strife Is ___, the Battle Done" (church hymn)

A lot of thinking is done in them

Church bells sound, I know, you wouldn't know as you're a heathen who's never stepped foot in a church before or even walked by one

Separation of church and church?