"Oh!" this appears to fluster her a little, but she turns around and fishes a Bible out of her bag. "Certainly, if you'd like, uh. This is the start of the passage: 'Every generous act of giving, with every perfect gift, is from above, coming down from the Father of lights, with whom there is no variation or shadow due to change.'"
She looks up and says, "Variation or shadow here is continuing the metaphor started in 'Father of lights'. It implies that God is a light, but unlike a physical open flame lamp, can't be shifted around by the wind, so that the light becomes less easy to see by."
"'In fulfilment of his own purpose he gave us birth by the word of truth, so that we would become a kind of first fruits of his creatures.' So we are a sacrifice, or rather a dedicated offering. First fruits is short for a dedicated offering made yearly." She looks shyly at Arthur. She very rarely talks this much unless she's behind a pulpit, and it makes her a bit uncomfortable.