Ignore the spicy headlines – Killjoy Pope Crushes Christmas!

Benedict Says Angels Don't Sing! No Ass And Ox In The Stable! – this isn't a book for the lay or casual reader.

The glossy cover, cashing in on the celebrity author and the Christmas market, is pure commercialism; both Bloomsbury and Benedict (who surely is against using the birth of Christ as a marketing opportunity) know that his third and concluding volume on Jesus of Nazareth is really for exegetes and academics.

You need a Bible on hand for one thing, or a concordance; Joseph Ratzinger refers to chapters and verses from both Testaments without providing the text. His prose is scholarly, though not without a certain clipped elegance. It will be of use, undoubtedly, to Catholic scholars and perhaps critics of other persuasions who wish to pick a fight, for whereas the headlines are juicier-sounding than the arguments themselves, The Infancy Narratives comes dangerously close to counting angels on pinheads.

To satisfy curiosity: Benedict does indeed conclude that angels don't sing. However he grants that angels' voices are of such dulcet beauty that they must sound like music to mortals' ears – an unusually pretty idea in an otherwise austere interpretation of the nativity.

As for animals being present, he becomes uncharacteristically literalist, noting that they're not actually mentioned in any of the Gospels. (In fact he deduces that the ass and the ox represent Jew and Gentile, though thankfully – his tact having failed him before – does not say which is which.)

The methods of discourse will be familiar even if you are not a follower of Christology. Anyone who reads political books, or newspapers for that matter, will recognize the practice of choosing sources to fit the argument.

When the words of the original evangelists don't provide what Benedict requires then he finds it in the works of other theologians or historians or in the Old Testament. No more unexpected than a Marxist, say, or a Keynesian, or philosopher searching for evidence when the source material doesn't give what he needs.

Benedict XVI is a profoundly conservative pontiff; it's hardly surprising that he's equally traditionalist in his theology and prose. I doubt any Catholic will be surprised at what he has to say here. More relevant to the ordinary reader is Canongate's wonderful collection of Biblical books with their introductions by unexpected writers, and the Gospels themselves, with all the passion, contradiction, marvel and truculence missing here.

Ratzinger is speaking to the converted, clarifying tiny details within a generally accepted Roman canon. You will not find what is remarkable and moving in the nativity, even to the non-believer.

The story of the birth of Christ seems to me singular in religious thinking, having at its centre tenderness and nurture, rather than threats and commandments.

The main players are a woman and a newborn, with all that implies about the sacred feminine and innocence.

The Infancy Narratives is less interested in the political significance of the poverty and rejection into which Christ was born, preferring to emphasise the doctrinal meaning of a birth amongst the poor of the earth.

The power and poetry of the nativity is not dependent, for most people, on doctrinal law, or the fact that it might be derived from pharaonic or other creation myths. And there is more than enough intellectual muscle in it to swim against the gush of sentimentality.

If you are already well versed in the theology of the Virgin birth and concerned more with its ecclesiastical than its societal and cultural implications, the final instalment of Jesus Of Nazareth will surely be of interest.

If it's a Christmas read you're after, an inquiry into an event that has had a fundamental effect on the world – for good and ill – there are more elementary books around.