THX1138, Bach, and the Meaning of Being

Why do you suppose George Lucas scored the final escape scene in THX1138 with Bach's Kommt, Ihr Tochter?

Come, you daughters, help me lament,
Behold! - Who? - The groom!
See him! - How? - As like a lamb!
O Lamb of God, innocent
slaughtered on the trunk of the cross,
See! - What? - See the patience!
Ever invented patiently,
Although you were despised.
Look! - Where? - Upon our sins!
You have borne all your sins
Otherwise we would have to despair.
See him out of love and grace
Carry the wood of the cross yourself!
Have mercy on us, O Jesus!