Gluck represents Christian Socialism in The King of the Golden River in that he shares his prosperity with others. At the end of the tale, Ruskin says that "the poor were never driven from his door," and throughout the narrative, he is opposed to his elder brothers in his altruism.
Ruskin's principal critique of capitalism, as seen in the conduct of the two elder brothers, Hans and Schwartz, is that it is insatiable and destructive. The brothers are wealthy, living in and ruling over the rich farmland of the Treasure Valley, but they are never content, always wanting more wealth and (unlike Gluck) jealously guarding everything they have:
They killed everything that did not pay for its eating. They shot the blackbirds because they pecked the fruit, and killed the hedgehogs lest they should suck the cows; they poisoned the crickets for eating the crumbs in the kitchen, and smothered the cicadas which used to sing all summer in the lime trees.
Hans and Schwartz also destroy Gluck's golden mug out of greed and malice, as Ruskin believed the capitalist would always destroy beautiful things. Through his kindness to others, which contrasts with the selfish conduct of his brothers, the altruistic, Christian Socialist Gluck is able to bring prosperity back to the Treasure Valley.