When discussing the merits and qualities of sacred art, a distinction is often made between art that has a didactic function - primarily for teaching purposes - and liturgical art which is intended to deepen engagement with God directly and during the liturgy itself. It is commonly said that in the Roman Church the focus for the production of art has been didactic, at least since the time of Gregory the Great (who is often quoted in this regard); whereas in the Churches of the Byzantine Rite the focus, it is maintained, is on deepening engagement with the liturgy and so is more authentically liturgical. This distinction is made by some to explain what is perceived as the inferiority of Western art in relation to Eastern iconographic art.

Didactic art, it is assumed, engages the person through, primarily intellect, deepening the understanding of salvation history or of a feast. Liturgical art, on the other hand, it is said, engages the heart of the person, and engages both the intellect and will in an ordered and balanced way so that the whole person is directed to the contemplation of God through worship of Him. 

In practice, however, I would say that this distinction is exaggerated. Good examples of Western 'didactic' sacred art engage both the intellect and the will if it is to be effective in its function. After all, art that is intended to be didactic must be beautiful enough to engage the will as well as the intellect so that we want to understand and be open to accepting its message - taking it to heart, so to speak. Further, if what it teaches us directs us to the liturgy simultaneously, which is quite possible, then it will enrich our worship, and so can be considered liturgical.

Similarly, good liturgical art is inevitably didactic also. The content of Eastern icons can be described and explained to us so that we understand its scriptural roots, for example, and the Feasts more thoroughly, so engaging the intellect strongly. There are excellent books that do just this and they draw heavily on scripture and the teachings of the Church Fathers in doing so. I have recently featured a wonderful example written by Aidan Hart, the Orthodox iconographer.

If the result is, in each case, that the person is drawn into a deeper participation in the liturgy, then for all the differences in the description of the intended purpose of the art in the mind of the artist or those who commissioned it, the dynamic here between art and viewer is likely very similar. Good didactic art is simultaneously liturgical, and good liturgical art is simultaneously didactic. The assumption made by critics of art made by Roman Catholics that the art was created to exclude the liturgical function is not necessarily true.

So, for example, gothic windows are often described by art historians as the scripture in images that teach the illiterate. But the truth is that they cannot be an alternative to scripture - no one looking at this picture of Seth and Adam, would know the story without either hearing it or reading first. The primary form of teaching even with such a window is either the written word, or word of mouth. Once we know the story, however, looking at such an image is likely to bring to mind, in a single moment, not only the narrative from Genesis associated with it but all the theological implications that this narrative has. And as these truths have relevance every time we worship, this window has a clear liturgical function.

In order to know how well it performs its function, we would need to know if, generally, its effect is to distract from the liturgy or to direct people to it and this will be as much a consequence of its style as its content. We can never say definitely what goes on in people's hearts, but generally, the gothic style, as much as the iconographic, is cited as having a positive effect in this regard in the context of the Rite it was created to illumine, that is, the Roman Rite. As a rule, liturgical art styles must have a balance of naturalism and abstraction so as to create a recognizable image, that has inbuilt into it a degree of dissatisfaction (due to the symbolic quality imparted by controlled abstraction) that leads us to move beyond the image in our imaginations, and to God.

There is another category of religious art, which has a purpose that is distinct from traditional church art and that is book art - ie illustration or illumination. One might say that the purpose of the illustration of sacred texts is primarily to direct us to the words in the book, so enhancing the power of the words lead us to God. This is a noble function certainly but is secondary in importance to the function of the art I have described above. The style of art that we might see in a children's bible or a Latin Mass Missal would, in my opinion, fall into this category. The examples I show below are not presented as bad art, but as good art which fulfills its function of illustrating a text very well. In my opinion, the style is too naturalistic to be considered authentically liturgical.

However, there can be a blurring of distinctions here too. For texts that are read many times and so are familiar to the reader, the sense that the words contain can be brought to mind in an instant, as described above with Seth and Adam in the context of the liturgy. When this happens, the art won't lead us back to the words, rather it leads us from the words, via meditation on the passage, to the contemplation of God. I suggest that images that are more likely to do this, will be illustrations painted in liturgical styles, as one might see in an ancient psalter.

Such art, if viewed often in conjunction with the text, by being impressed upon our memories can be drawn upon by the imagination when we hear the words of the psalm, say, in the context of the liturgy, and so in this way can have a clear and even more direct liturgical function, albeit in a less direct way than liturgical art that hangs on the walls of the church. I suggest the best ‘illumination’ work in sacred art will fulfill both an illustrative and liturgical function (and hence is didactic as well!).