What on earth did He look like?

How do you write about Christianity and how do you write about art? These two books approach these two key problems in their different ways and offer different solutions. The Image of Christ, the catalogue of the exhibition "Seeing Salvation", is very much a traditional catalogue to accompany an art exhibition. An introduction sets the scene, telling us something of the motives behind the exhibition, and the bulk of the text then describes the works on display. This catalogue is arranged in seven thematic groups, covering some of the different issues involved in the depiction of Christ: his dual nature as man and god, the question of true likeness, the portrayal of his body as sign or symbol or through signs and symbols. Painting the Word is, however, a more interpretative piece. It aims to explain how Christian paintings convey their messages through composition, content and iconography.

Both are subjective pieces, in that they are necessarily selective in what they tell us about the works of art they discuss. A catalogue cannot tell everything about each work; the writers of each entry choose what information they feel is most useful to the user of the catalogue within its specific context. Thus Holman Hunt's Light of the World , which here appears under the heading of "Sign and Symbol", might have contained different information had it appeared under the heading "The saving Body" or even "The True Likeness". This is the nature of catalogues and indeed of exhibitions. A criticism of "Seeing Salvation", the exhibition, was that the images did not cohere in ways that some reviewers would have liked. The catalogue, however, is a good, solid, intelligent and well-produced book and provides a rationale for the categories and groupings of the exhibition, revealing the inherent fluidities and power of Christian art. Indeed, one of the features of the exhibition was the number of visitors who responded to the images in a spiritual and emotive fashion, a striking testimony to its effect. My caveat, with catalogue, exhibition and television series, is different and lies in the deliberate emphasis on western and very largely post-medieval Christian art. This seems a pity. Western medieval and Byzantine Christianity wrestled constantly with the issue of the difficulties for Christian artists in representing Christ, and their debates, hardly articulated here, underlie much of what is presented.

John Drury's book offers a different approach. It does not aim to give us "facts", but to tell us what the picture under study is about. This is the genre of writing about art most recently popularised by Sister Wendy Beckett. It involves the telling of the story of the painting and the interpretation of the emotions perceived within that picture. The classical writers had a word for this; they called it ekphrasis , the rhetorical description of anything, from crocodiles and cities to works of art. Drury tells us what he can see in the paintings and he aims to recreate the story the paintings tell for us. He ascribes feelings and emotions to the characters portrayed, to the painters involved, and he narrates a story in which fact ( The Vendramin Family was painted by Titian between 1543 and 1547) and interpretation ("the children are fidgety" in Titian's Vendramin Family ; Richard II's eye has "a bright and attentive vivacity" in the Wilton Diptych; Cezanne does not believe that the ex-nun in his An Old Woman with a Rosary has lost her faith) interweave seamlessly. To create this effect, he juxtaposes elements across time and space. The medieval poem Pearl and Wordsworth sit side by side in explaining the Wilton Diptych ; Edwin Muir and Cima make the same point. Thus art becomes universal, a reflector of some imagined eternal "truth" or emotion, a truth which appears as objective but is, instead, deeply personal.

This is a very different form of writing about art from that of The Image of Christ . That book is what might be defined as art history - the fitting of objects into a historical context and the use of that historical context to gain understanding of the way in which those objects functioned in the past.

Painting the Word is what could be called "artful historical fiction". Like a Catherine Cookson novel, it creates feelings and emotions through a narrative set in the past so that we believe that these feelings, emotions and responses are real (Mary is perturbed or maternal) and also universal. Drury, like Sister Wendy, and indeed like Neil McGregor in the television series, looks for the reactions that we in the 21st century can apprehend. He translates the art into our terms, which are disguised as universal terms.

But we write about art in our own image. Are those children in The Vendramin Family fidgety, transfixed or perhaps scared? As we select an emotion to ascribe to them, so we can change the story. Am I the only person to think that the angels in the Wilton Diptych look supremely bored and fed up with proceedings? Some critics felt that Sister Wendy displayed an un-nunlike interest in physical appearance and lust in her story of art and that this coloured her approach.

Drury's concern is different. He declares at the start of his book that he has come to believe that the New Testament gospels are "works of imagination and often forcefully fictional". This is the message that underlines his descriptions. He writes a story about events that he perceives to be essentially fictional and that, at some level perhaps, he feels his artists may also have believed to be fictional. He never makes it quite clear whether he aims to look at these pictures in their terms or in his. In the end, I had a sense of what these pictures meant to him but nothing of their place in their own past, nothing of their own stories.

In this way, Drury's is a perceptive but undemanding book. It is, as the blurb says, a book "about pictures", a phrase which is essentially vague and meaningless. It is easy to say what you see in a picture, what it means to you. This is a book that does not challenge us with any of the hard questions.It offers us an easy way out from the question of how to depict a god who became man. We do not really think this happened, so it does not really matter.

This leaves unspoken the historical context. What did these images mean to "them"; how did "they" see and respond to them? Drury's painters believed the story that they told, that God was man. In a way almost impossible for us to grasp, the past believed in the Christian message, that the Bible was gospel truth. In explaining the pictures to us, in telling us his story, Drury has lost this sense. In the Byzantine world, the Christian ekphrasis was supposed to "understand ultimate things and open secret places"; it was not a simple narrative but aimed to make clear to the listener the hidden truths of the picture, to confront the vastness of God depicted as man. The emotion in the picture seen by the viewer was meant to create a corresponding emotion - people rejoiced in front of the nativity, wept in front of images of the crucifixion. The picture of Christ was Christ, a veritable painting of the Word. In Orthodox Christianity, the image carried far greater significance for the believer, for the image was, quite simply, the person depicted.

In western Christianity, this was not the case. The image was just a picture. It is thus perhaps no accident that neither Drury nor Seeing Salvation confronts the Byzantines. As the catalogue shows, these images were still objects of devotion and their viewers believed the story they told. As the response of many visitors to the exhibition tells us, these pictures have the power to move the viewer in ways which Drury's ahistoric subjectivity does not.

Liz James is senior lecturer in the history of art, University of Sussex.