"I really cannot bear an immoral man. I am not a Pharisee, I hope; and I should not have minded his merely doing wrong things: we are none of us perfect. But your father didn't exactly do wrong things: he said them and thought them: that was what was so dreadful. He really had a sort of religion of wrongness."
In one of Lady Britomart's first lines, the core beliefs of her character are revealed: a firm sense of morality, and a strong, undeterred opinion that Andrew Undershaft is a wicked, immoral man. This belief is what she has preached to her children, and instilled in them. It hints at a time where one of her children may come to eventually challenge, and reject this judgement of his character.
"For me there is only one true morality; but it might not fit you, as you do not manufacture aerial battleships. There is only one true morality for every man; but every man has not the same true morality."
Andrew Undershaft reveals his own thoughts on morality; it is an abstract, multifarious object that changes depending on the person. Each person holds their own version of what they find honest and right, or their "true morality". To him, there is no overarching statement that can define morality in all people, for it is a shifting, inconstant thing.
"My religion? Well, my dear, I am a millionaire. That is my religion."
Here, Andrew is revealing the crux of his character. He is completely obsessed with wealth and riches, to the point that he declares them his "religion", essentially worshiping money as his God. It also provides insight into how he sees the world: Wealth is a form of divine reward or retribution, which is why he sees Sarah's work as a waste of time.
CUSINS. I have never before ventured to reproach you, Lady Brit; but how could you marry the Prince of Darkness?
LADY BRITOMART. It was much more excusable to marry him than to get drunk with him. That is a new accomplishment of Andrew's, by the way. He usen't to drink.
This quote shows several important things at the same time. First, it shows the restrictions on behavior and gender at the time. It was easier for Lady Britomart to marry Andrew, "the Prince of Darkness," than to grab a drink with him! Second, it shows Shaw's satirical views of the moral views of the British upper class. Later, Cusins and Lady Britomart will engage in mental gymnastics to convince Barbara that helping the poor through the Salvation Army is less valuable than Andrew's ability to help the poor with jobs making weapons.
UNDERSHAFT. He knows nothing; and he thinks he knows everything. That points clearly to a political career.
This line is pretty funny if you are cynical about politicians, but moreover, this line is another example of the complex ideology of the play. Andrew is here describing Stephen, his grown but estranged son. One of the tensions in the play deals with the conflict between faith in one's ideology and the evidence around them. To Andrew, Stephen is an obnoxious youth who has no experience but plenty of confidence. To Stephen and some of the other characters, Andrew comes across the same way.
