What does Undershaft mean when he identifies "money and gunpowder" as necessary to salvation in Major Barbara?
It is important to realise that Undershaft presents an "alternative" gospel and creed on which to base one's life. Just as Cusins is evangelical about his "gospel," so is Undershaft equally zealous about his beliefs and approach to the world. Note what he says to Cusins:
It is the Undershaft inheritance. I shall hand on my torch to my daughter. She shall make my converts and preach my gospel.
This gospel is of course based on "money and gunpowder; freedom and power; command of life and command of death." Undershaft thus reveals that in his view, power lies in might, and might lies in weaponry. With "money and gunpowder," Undershaft believes that he has true power in Europe, as these two objects are the basis of warfare and modern political power. He deliberately eschews belief in an omnipotent God and believes salvation can be found from following these two objects. For Undershaft, religion is misguided in the focus that it places on personal sin. Mankind does not need salvation from such sinfulness, but he definitely does need salvation from the wider societal ills that keep him in a position of poverty, illness and want. To his mind, Christianity must be rejected because of the way that it stands against money and war. Actually, these are the only means of true salvation. In particular, note the way that Undershaft's purchase of the Salvation Army "proves" his position, as it demonstrates how salvation is only possible because of people who have the power of money and gunpowder.