What is the theme in Knowledge of Angels by Jill Paton Walsh?

Godly purposes vs. coincidences is a theme in the book. Knowledge of Angels begins with a series of coincidences that some of the island's religious leaders originally believe must be part of God's larger purposes. Palinor insists that he washed up on Grandinsula, because he swam in that direction, but Severo and Beneditx tell him that God brought him there for a reason. Severo also later interprets the discovery of Amara, a child who has endured terrible hardships and a gang rape, as a way for them to learn whether knowledge of God is innate. In reality, Amara was raised by wolves, because her mother, a slut, gave birth high in the mountains and a wolf stole her twin babies.