What the hell is this song about?

The Tudor king whose wedding ring brought down his loyalty
must finance his defense against his foes across the sea
"Defender of the Faith" would soon forget his piety
when the crows come home to roost

The land's religious houses seemed such a tempting prize;
Treasures in each cloistered wall -- so it was no surprise
that Thomas Cromwell's survey found them sinful and despised
when the crows come home to roost

  Stripping all that's sacred, they'll plunder as they please
  Gleaning all the gilt from every door
  Toppling all the towers that hold our histories
  And nothing is sacred anymore

Now one by one each monk and nun is cast out on the ground
The lands all sold or parceled out to lackeys of the crown
Each nunnery and chancery are auctioned or torn down
when the crows come home to roost

Every house and abbey left abandoned to decay
Every quiet cloister where the pious used to pray
Every nave and chancel's sacred relics borne away
when the crows come home to roost

 [chorus]

Half an eon later, and half a world away
The canvas-clothed invaders come conquering from Cathay
Every prayer powerless on this disastrous day
when the crows come home to roost

Every ancient temple purged as old bourgeois debris
A cultural revolution that would wipe out piety
Another peaceful people, robbed of their history
when the crows come home to roost

 [chorus]