Themes are the fundamental and often universal ideas explored in a literary work.

Arms and the Man

Known as one of Shaw's "discussion plays," Major Barbara is primarily structured through a series of conversations on morality, religion, and social engineering. The primary topic of discussion is what Shaw identifies in the preface as the "Gospel of Saint Andrew Undershaft," that is, the gospel that would promise society's redemption.

Undershaft's gospel is organized around the apotheosis of the millionaire and, more specifically, the military industrialist. As the characters will come to realize, the world is not in God's power but in the power of the military industrialist. With money and gunpowder, Undershaft participates in the power that reigns over Europe, the power that determines the course of society. This re-organization of society, rather than one's faith in a religious doctrine, provides the means of salvation. For Undershaft, man does not need redemption from sinfulness but from the material abjection of poverty, hunger, and sickness. The growth of Christian virtues rests fundamentally on man's material security. Undershaft wants nothing to do with a religion that abjures warfare and wealth. These evils are the necessary means by which man can be saved.

Though initially resistant, the democratic Cusins will soon convert to Undershaft's gospel and become his successor. Barbara will return to the Salvation Army with this gospel as well, recognizing that the necessary dialectic between good and evil means that the work of salvation requires the pact with the Devil. They both come to realize Undershaft's power upon the demonstration of his authority over the Salvation Army, a purchase that reveals how all work of salvation is indeed contingent on those who hold the money and gunpowder.

Unlike Undershaft, Cusins takes up the armory in the name of a love for the people. Through the armory, he will abandon his anachronistic and intellectualizing studies and make power for the contemporary world, a power accessible to the masses and that forces the "intellectual oligarchy" to exert itself for the general good. He too exalts the arm as the force that stands to destroy all forces and determines the course of the world.

The Will to Killing

Undershaft's philosophy also organizes itself around a notion the great man's "will." This will comes into being through the agonistic struggle between men. As Undershaft proclaims, a sacred commandment, "Thou shalt starve ere I starve," sets him on the path to greatness. Through a murderous struggle with others, Undershaft realizes his will and desire. Thus his "bravest enemy" is his best friend, a rival who keeps him "up to the mark." Over and against Christian ideals of human brotherhood, the recognition Undershaft demands from his neighbor is not love but obedience and respect, a bending to his will. Again, the struggle he stages with others is decidedly violent. Those who do not submit to his desire must die.

Such killing in the name of the will does restrict itself to those who stand in the way of the great man's desire, but extant social structures, institutions, and ways of thinking as well. Killing is the means by which the moralist's "ought" becomes a "shall"; it is the "only way of saying Must." Only the murderous command can inaugurate the new that follows necessarily according to the will of the great man. Until he achieves his will, he is menace to civilization; upon its realization, he becomes its benefactor. Thus, the great man makes history.

The Ideal Community and the Crime of Poverty

Major Barbara is structured by a contest between father and daughter for the other's soul and the path of salvation. Each agrees to visit the other's workplace and allow the other to attempt their conversion. Undershaft's visit to the Salvation Army shelter takes place in Act 2; Barbara goes to the armory with her family in Act 3.

As discussed in the preface, Shaw's portrait of the shelter is fundamentally a critique of the Salvation Army's flaws. One of the many criticisms Shaw underlines, for example, is that the Army forces its clientele to pander to the saintliness of its workers. In this sense does the work of the Army have less to do with the condition of the poor than the narcissism of its officers. More importantly, the Army fails to realize that man does not need redemption from sinfulness but from the material abjection of poverty, hunger, and sickness.

Unlike the shelter, Perivalee Saint Andrews appears as a paradise of social engineering. Undershaft has redeemed his men more successfully than preaching ever could by eliminating poverty. He does not do so for the love of the masses. Certainly Undershaft provides for their comfort to assure his company's productivity. He also, however, considers poverty the worst of man's crimes. For Undershaft, the "crime of poverty" is a crime committed against society by the poor themselves. The poor, appearing as abject masses from some paranoid fantasy, "kill" society's happiness, forcing the ruling class to eliminate its liberties and organize "unnatural cruelties" to keep them in check.

Thus Undershaft will pit himself against poverty in the name of order and cleanliness. Indeed, for Undershaft, order and cleanliness are categorical imperatives of sorts—they justify themselves. Though the realization of these imperatives would ostensibly benefit the masses, we can readily imagine how they might come at their expense as well. Simply put, the institution of order and cleanliness easily means the elimination of the disorderly and unclean. Note in this respect Undershaft's chilling invocation of the Salvation Army's motto in Act 1: "My sort of blood cleanses: my sort of fire purifies."