What is the theme in The Great Gilly Hopkins by Katherine Paterson?

One major theme in the novel, The Great Gilly Hopkins, is that of the Christian faith. Religion, specifically Christianty, plays a large role in the novel's plot, as belief in God and Jesus the Savior, as well as adherence to the tenets of the faith are genuinely illustrated throughout the novel, and in the actions of its characters. Faith, hope, and charity abound.