Margaret Barker, The Great Angel: A Study of Israel's Second God, (London: SPCK, 1992).

Here's the summary statement on the back jacket:

What did "Son of God," "Messiah," and "Lord" mean to the first Christians when they used these words to describe their beliefs about Jesus? In this groundbreaking, clearly written book, Margaret Barker goes against protocol and treats these three titles collectively. She explores the possibility that in the expectations and traditions of first-century Palestine they belonged together, and that the first Christians fit Jesus' identity into an existing pattern of belief. Barker claims that pre-Christian Judaism was not monotheistic and that the roots of Christian Trinitarian theology lie in a pre-Christian Palestinian belief about the angels - a belief derived from the ancient religion of Israel in which there was a High God and several Sons of God. Yahweh was a Son of God, manifested on earth in human form as an angel or in the Davidic King. Jesus was a manifestation of Yahweh, acknowledged as Son of God, Messiah, and Lord.

Barker supports her thoughtful investigation with canonical and deutero-canonical works and literature from Qumran and rabbinic sources. Her stimulating book will shed new light on the origins of Christianity and is an excellent source for Old and New Testament scholars and anyone interested in Jesus as a person.

Margaret Barker is a teacher at Ockbrook School in England. She is a member of the Society for Old Testament Study and author of The Lost Prophet.