Formal religious order
If someone asked Kate and Baba what their life was like during their teenage years, they would have said those years were burdensome and filled with rules. The rules are a derivative of religious obedience, so that the imagery of formal religious order impacts each girl's opinion about God and morality. They are literally indoctrinated in a formal religious education whose explicit goal is to forbid them from sin until they complete their education. This imagery is well-known to some and completely foreign to others. There are entire civilizations that rise and fall with this kind of imagery intact.
Sexual repression
If a person is happy to sacrifice sexual appetite for personal growth and religious devotion, then certainly that experience can be very fruitful and peaceful, but when the person is forced to abdicate their sexuality under threat of religious shame, then psychological experiences are warped and sexual repression appears. One might say that the abstract imagery of Kate's relationship with Baba is a dual expression of the effects on different people; in Kate, we see the obedient and trusting approach who wants to believe that the religious authority of the Catholic church is divine, in Baba, we see a rejection of patriarchal authority systems, and surprisingly, that seems to be the more ethical display.
Failures in empathy
One of the reasons that the reader gets the impression that Baba is a more ethical person than Kate is because of imagery. There are signals in the prose where body language and implication suggest that Kate secretly thinks she is the more morally competent person out of the two; in reality, she is just failing to practice empathy. The imagery of empathy is evidenced by its lack in this novel. Kate will not extend the empathetic benefit of the doubt to her best friend Baba, so she also fails to respect her own sexuality, choosing instead to build her identity on dissonant ideas about herself.
London imagery
London is a fitting site of imagery for Kate's emergence from repression, and the reader hopes that through these experiences, she will abandon her short-sighted moralism, but in fact, she proves herself to be kind of a hypocrite. That is one way of seeing London. The other is more generous: One can say that London challenges Kate to face her shadowy unconscious to address false beliefs in her opinion of herself. When she rejects Baba, she rejects the part of herself that is essentially like Baba, showing that she is confused about moral goodness. She genuinely believes God hates her if she sins, and that idea demands more time to untangle than this book covers.
