Cardinal Cormac Murphy-O’Connor’s suggestion last week that Piero della Francesca’s Baptism of Christ might be taken down from the walls of the National Gallery and displayed in Westminster Cathedral caused widespread interest, as if he were saying: “It’s ours, give it back.”

In fact his point was that the painting, while a masterpiece, is much more than a work of art. Rather, it is a work of faith. This, rather than the notion of a Cardinal-led raiding party of our notable galleries, was the truly surprising point. For if there is one Christian value that is in danger of being forgotten, it is the aesthetic.

For most Christians, their religion is about “the good” — the ethics that are part of our core beliefs — and “the true” – what they assent to, what they believe. The way believers serve their community, and the way they treat others, is essential to being Christian. So too are the truths held dear — the creed of the faith.

And yet Scripture refers continually to something else as well: to what theologians would call the disclosure of God’s glory. That means, in lay language, that not only the good and the true are integral to our faith but so is beauty. Our aesthetic experience is a source of values as well.

Pope John Paul II spoke on several occasions of the importance of beauty, saying that the beauty of Man, conveyed in the work of artists, expresses the beauty of the Creator. And in the Creator, he said, truth, goodness and beauty are as one. Michelangelo’s Sistine Chapel, he said, was like a sacrament. The mystery of the Incarnation is revealed to us through such great works of art. They are visible ways of communicating the invisible.

Christians have an extraordinary heritage, thanks to the genius of men and women who have conveyed faith through the arts, from Leonardo to Michelangelo, from Bach to Mozart. The simplest images make use of creative talent to connect us to God. Some years ago I took two friends with no religious background to Assisi, and as we looked at Giotto’s frescoes I told them the story of St Francis and tried to explain something of the Christian faith that so inspired him and in turn the painter. They were noticeably moved. I suspect this is because great art is one way in which those who have had no connection with religion do find a glimmer of God. Without faith, the aesthetic experience can indeed be an empty one, but it can also lead to transcendence, to a connection with the divine. That is a good reason for keeping Piero della Francesca’s Baptism where it is.

The way in which beauty can be a a way into God — into the good and the true — is also evident at the Byzantium exhibition at the Royal Academy, where among the most stunning of the exhibits are the icons. The word icon has been cheapened nowadays. Every celebrity is an icon — of pop, of movies, of football. But the true icon is not to be idolised. A true icon is a window into the mystery of God and the mystery of our lives. It is a point of contact.

The Christian religion is remarkable for the way in which it makes so evident that God is incarnate among us. He took flesh, He was real as we are real, and the physical matter of the world that we use in our liturgical rituals — water, wine, bread — makes our bond with God. So the stuff of art is also used to reinforce that bond. But people of faith for too long seem to have taken for granted the importance of this bond that the aesthetic makes between us and God. We think of our faith as being about shared values, about worship, about our creed. But beauty — what we create and that of the Earth — is part of the essence of faith too. And of course, there is a special kind of beauty that we find in character too, in people of integrity. No wonder, then, that Dostoevsky once said: “The world will be saved by beauty.”

Catherine Pepinster is editor of The Tablet, the Catholic weekly