Capitalism vs Socialism
The very basis of the novel The Iron Heel is Socialism, and the struggle of Ernest Everhard, a Socialist philosopher from the working class or proletariat, to destroy Capitalism from the roots and establish a just socialist government. The whole book is founded on Socialism. Ernest Everhard's philosophy establishes the socialist and Marxist views of the author Jack London in the novel, while Capitalism is replaced by a worse reality of an Oligarchy where the rich and the people on the top of the social ladder get richer and powerful; while the poor of the working class are even denied justice. This is the basic theme which dominates the other themes in the novel like rebellion, war, unequal distribution of wealth, power play, media, religion, etc.
Rebellion and War
The whole novel is about the rebellion of Socialists against the Oligarchy. The socialists like Ernest and Avis Everhard, John Cunningham, Bishop Morehouse, etc., readily give all they have; like their jobs, money, safety, and even their lives; for the success of the rebellion, so that a better government could be established. This they plan to bring about by war, and hence both these themes go hand in hand in The Iron Heel. The revolutionists do not have the power to bring change any other way, as the Oligarchy doesn't care for the proletariat in any way other than to abuse them. This is clearly seen in Ernest's statement, "Our strength, the strength of the proletariat, is in our muscles... in our fingers to pull triggers... it is the strength that is stronger than wealth, and that wealth cannot take away."
Unequal Distribution of Economy
This is considered by all socialists as the root cause of all the injustices seen in the society. In The Iron Heel, this is named as the very basis of the rise of Oligarchy, which is a monopoly controlled by various successful trusts. Ernest mentions the Rockefeller's, which was 'the first successful great trust' as an example of this monopoly, which starting with just the oil industry, branched out into various other fields. These trusts by doing business on a large scale wiped out the small scale industries, making them bankrupt. The Milk Trust, for example wiped out all the Milkmen out of their jobs. As these trusts grew, more power came into their hands, creating the Oligarchy, and bringing even more power to them, creating an even more unequally distributed economy. It is basically against this that the revolutionists fight.
Religion
With the rise of the Oligarchy, religion also gets manipulated. As Everhard says, "The Church is not teaching Christ these days... The Church condones the frightful brutality and savagery with which the capitalist class treats the working class... for remember the Church is supported by the capitalist class... The proletariat has grown up outside the Church and without the Church." Bishop Morehouse is sent to a madhouse when he protests against the capitalistsm in the church. In contrast, Dr. Hammerfield and Dr. Ballingford modify religion for the sake of the Oligarchy and so get much rewards from them. This is why the revolutionists stand against and hate the church throughout the novel.
