What is the main idea?

Because of Winn-Dixie follows a young girl named India Opal Bulloni, who has just moved to the new town of Naomi, Florida, and is facing life with no mother and no friends. She lives alone with her father, an emotionally reserved preacher in the Friendly Corners Trailer Park. Opal and Winn-Dixie are destined to meet. When Opal happens upon the troublemaking stray in the local supermarket, she knows that she cannot condemn the friendly dog to the pound. The story is centered around the theme of friendship.