When presented with a book by James Dunn, one knows it will be worth reading, and this is no exception. Choosing a challenging topic, he meticulously works his way through the argument examining both Biblical text and interpretations by current key thinkers. He examines the elements of the title – worship, its language and practice among early Christians; and the relationship between and nature of God and Jesus, Father and Son, divine and human. A clue to the conclusion lies in the difference between idol and icon. With copious footnotes, bibliography and indexes to Biblical references, the writings of modern authors, and subjects covered, that a PhD student writing a thesis should use as a guide as to how to do, the resulting book is, firstly, a good read in itself, and, secondly, an introduction to the scholarship of this subject area.