Beauty is Truth and Truth Beauty. That’s all you need to know.
Beauty is attractive. It draws you in. It is an experience. I know a young priest who was raised a Baptist and went into a beautiful Catholic Church when he was fifteen years old. He immediately knelt and knew he was not only going to be a Catholic, but that he was supposed to be a Catholic priest. Beauty in a Catholic Church is something ‘crazy’ for God in a brutal utilitarian age. But that beauty speaks of the attraction of God himself and it helps to draw us into his presence.
Why should Catholics build beautiful churches? First, because beauty is eternal and the Catholic faith is ever ancient and ever new. God’s love is eternal and the Catholic faith will last until the end of time.
Something that is beautiful improves with age, and so with the Catholic faith, and therefore a beautiful Catholic church speaks of the antiquity and permanence of the faith it proclaims.