"Morality, like art, means drawing a line someplace."
One of the more interesting arguments against Catholicism, from an artistic perspective, is that in living by a single truth, diversity is limited. But what about the alternative?
If you believe that there is no God, no objective truth, how is infinite diversity possible? Even the abyss of the universe is finite. And the answer isn't simply to do what hasn't been done. If art is simply pushing the limits and doing what no one else has done, you're being original without being creative. Art becomes limited to the created world, by the created world.
In the converse, when art is meant to more than entertain, when it reaches towards objective truth, towards God, it is appealing to something that is infinitely more vast than the created universe. God is infinite, and He Himself is an artist. When art moves toward God, there will necessarily be elements in it that would be impossible to achieve by appealing to nature alone. Even when agnostic artists achieve some level of supernatural beauty, it is through the grace of God, not nature. With God, the possibilities, to be cliché, are endless.
On a completely unrelated note, Oscar Wilde rules. Pace a tutti!