Iris Murdoch considers the challenges of living a genuinely religious life within corrupt, secular society; her setting is England some ten years after the end of World War II. Some of The Bell's characters are involved in or attracted to a more traditionally religious calling, represented by Imber Abbey. Most of the others, however, are searching for an emotional and a spiritual commitment, which may be located within a physical place, represented by the Imber Court community. Iris Murdoch uses the concept of the underwater bell, which may be retrieved and reinstalled in this community place, as a concrete representation of these challenges and the diverse ways that the characters experience them.

Along with her consideration of religious themes goes her attention to human, corporeal matters. The characters experience sexual longings, which are sometimes acted upon and other times merely grappled with internally. Murdoch questions the institution of marriage and the social and emotional differences and identities that complicate relationships. She also explores generational differences; the influence of the Depression and the War have a strong, although sometimes implicit, influence, which manifests in the relationships between Michael and the younger Nick and Toby, as well as in the marriage of Paul and Dora.

The two young female characters, Catherine and Dora, embody these challenges and the different paths that life offers. Catherine has decided to enter the Abbey as a cloistered nun. Her complicated crisis of faith, including nearly taking her own life, precludes that possibility. Dora has taken a worldly path, first in marrying the older, cosmopolitan Paul and then by having an affair with Noel. Not anticipating that marriage would interfere with developing her own identity, she ultimately finds a rewarding path. Dora’s path to personal fulfillment includes her daring, if misguided, plot to rescue the bell—standing for the promise of unity between secular and sacred, past and present, and offering a hopeful path for England’s future. In contrast, Nick’s negative, duplicitous manipulation of the social system and Michael’s inability to commit, either to his sexual orientation or a religious calling, both offer dead ends.