Letters to Theodore is a series of real-life letters written to a real-life individual, Theodore Smith. He's a new Christian young man from an unchurched background and in his early twenties. As he tries to be a good Christian, he faces issues of Christian life at church and in the world that aren't addressed in church creeds and policies. He learns how to deal with those issues through a series of letters written to him by Christopher Miller, a man in his fifties and involved in church all his life.

Theodore thinks even older Christians would like to read the information about the practice of Christianity contained in these letters. Therefore, Letters to Theodore is a book for all who want to live a truly Christian life.