The references are obviously Christian in some cases, quite obscure in others.
Green grow the rushes is a reference to
Lyrics
I'll sing you two ho,
Green grow the rushes ho.
What is your two ho?
Two, two the lily white boys
Clothed all in green-o,
One is one and all alone
And evermore shall be so.
I'll sing you three ho,
Green grow the rushes ho.
What is your three ho?
Three, three the rivals,
Two, two the lily white boys,
Clothed all in green-o
One is one and all alone
And evermore shall be so.
Four for the Gospel makers
Five for the symbols at your door
Six for the six proud walkers
Seven for the seven stars in the sky
Eight for the April rainers
Nine for the nine bright shiners
Ten for the Ten Commandments
Eleven for the eleven that went to heaven
Twelve for the twelve apostles
I'll sing you one ho,
Green grow the rushes ho.
What is your one ho?
One is one and all alone
And evermore shall be so.
There is also a similarly titled R.E.M song.