The function of all art lies in fact in breaking through the narrow and tortuous enclosure of the finite, in which man is immerged while living here below, and in providing a window to the infinite for his hungry soul.
Thus it follows that any effort-and it would be a vain one, indeed-aimed at denying or suppressing any relation between art and religion must impair art itself. Whatever artistic beauty one may wish to grasp in the world, in nature and in man, in order to express it in sound, in color, or in plays for the masses, such beauty cannot prescind from God. Whatever exists is bound to Him by an essential relationship. Hence, there is not, neither in life nor in art- be it intended as an expression of the subject or as an interpretation of the object-the exclusively “human,” the exclusively “natural” or “immanent.”
The greater the clarity with which art mirrors the infinite, the divine, the greater will be its possibility for success in striving toward its ideal and true, artistic accomplishment. Thus, the more an artist lives religion, the better prepared he will be to speak the language of art, to understand its harmonies, to communicate its emotions.
Naturally, We are far from thinking that in order to be interpreters of God in the sense just mentioned, artists must treat explicitly religious subjects. On the other hand, one cannot question the fact that never, perhaps, has art reached its highest peaks as it has in these subjects.
In this manner, the great masters of Christian arts became interpreters, not only of the beauty but also of the goodness of God, the Revealer and Redeemer. Marvelous exchange of services between Christianity and art! From their Faith they drew sublime inspirations. They drew hearts to the Faith when for continuous centuries they communicated and spread the truths contained in the Holy Scriptures, truths inaccessible, at least directly, to the humble people.
In truth, artistic masterpieces were known as the “Bible of the people,” to mention such noted examples as the windows of Chartres, the door of Ghiberti (by happy expression known as the Door of Paradise), the Roman and Ravenna mosaics and the facade of the Cathedral of Orvieto. These and other masterpieces not only translate into easy reading and universal language the Christian truths, they also communicate the intimate sense and emotion of these truths with an effectiveness, lyricism and ardor that, perhaps, is not contained in even the most fervent preaching. – from The Function of Art (1952)