What is the main theme in the novel, Footsteps?

Footsteps is a coming-of-age story in which a boy becomes a man within the span of a few days, learning that not everyone is honest or genuine; that people who appear unattractive or unworthy may actually be the ones most worth knowing; that those who have the least wealth may be the most generous in sharing what they have; and that, in order to gain a friend, one must be a friend.