28 But the artist who is firm in his faith and leads a life worthy of a Christian, who is motivated by the love of God and reverently uses the powers the Creator has given him, expresses and manifests the truths he holds and the piety he possesses so skillfully, beautifully and pleasingly in colors and lines or sounds and harmonies that this sacred labor of art is an act of worship and religion for him. It also effectively arouses and inspires people to profess the faith and cultivate piety.
Source: Musicae Sacrae (Vatican.va)