The theory of the unmorality of art has established itself firmly in the strictly artistic classes. They are free to produce anything they like. They are free to write a "Paradise Lost" in which Satan shall conquer God. They are free to write a "Divine Comedy" in which heavens shall be under the floor of hell. And what have they done? Have they produced in their universality anything grander or more beautiful than the things uttered by the fierce Ghibbeline Catholic, by the rigid Puritan schoolmasters? We know that they have produced only a few roundels. Milton does not merely beat them at his piety, he beats them at their own irreverence. In all their little books of verse you will not find a finer defiance of God than Satan's. ... Blasphemy is an artistic effect, because blasphemy depends upon a philosophical conviction. Blasphemy depends upon belief, and is fading with it. If any one doubts this, let him sit down seriously and try to think blasphemous thoughts about Thor. I think his family will find him at the end of the day in a state of some exhaustion. (Chesterton, Heretics. Introductory Remarks)
I have to admit to not knowing a lot about what he is all aluding to. But it seems like an excellent paragraph. I wish I would get around to reading Milton and Dante, etc., but I may not make it. I don't even have time today to look up "Ghibbeline" and "roundel".
But the part about proper blasphemy needing some sort of belief makes sense. And hence, we know that Chesterton is right about it all. There is no "unmorality of art".
Apparently, this sort of thing, below, is a "roundel". Well, lacking art about as much as the abstract above.