“‘Vanity of vanities,’ saith the Preacher. ‘Vanity of vanities. All is vanity.”
Apparently the Joker never made it to the end of Ecclesiastes. But he understood the first half well enough. If nothing matters, it doesn’t matter. Not life, not power, not money (not even a large pile of it). Everyone dies, everyone burns. Everyone’s life is a hilarious joke. And the most annoying things in a world where nothing matters are the people who think it does. People like the Batman.
The Joker’s not representative of Satan. He’s not just a clever villain from the mind of Jonathan Nolan. And he’s not a symbol for anarchy in the modern world. He’s just a normal man who understands very well (better than most) all the death and blood and gore of the world, but just never made it to the Cross.