Pope Benedict published the last part of his trilogy on the life of Jesus on Tuesday (November 20), delivering an early childhood narrative, which strongly reaffirms the doctrine of the virgin birth as an "unequivocal" truth of faith.

The book, titled "The Infancy Narratives - Jesus of Nazareth", is 137-pages thick in its English version and being published simultaneously around the world in 21 languages.

It is expected to be an international best-seller like the previous volumes.

Divided into a forward, four chapters and an epilogue, it traces and analyses the gospel narratives from the birth of Jesus to his presentation in the temple at the age of 12.

The previous two volumes dealt with the adult life of Jesus and his public ministry.

The Church teaches that Jesus was the son of God and was not conceived through sexual intercourse but by the power of the Holy Spirit, one part of the divine trinity.

One section of the book is called "Virgin Birth - Myth or Historical Truth?"

In simple language that is academic yet still easily accessible to a non-specialist readership, Benedict says the story of the virgin birth is not just a reworking of earlier Greek or Egyptian legends and archetypal concepts but something totally new in history.