These two comic and slightly grotesque caricatures are less developed than the principal players, and Wilde uses them to comment on religion and morality.
The minister is an intellectual character who speaks in metaphors. He is a "typical" country vicar who refers often to canon law and gives fatherly advice. Absent-mindedly in charge of his parishioners' souls, he performs christenings and interchangeable sermons, depending on the situation. Occasionally, however, his mask slips, and an interior world of lusty desire for Miss Prism appears. Often absent-minded, but always spouting moral platitudes, he symbolizes Wilde's view of Victorian religion and respectability.
Miss Prism is also intellectual, but in a literary way. She is a creative writer and a parody of "a woman with a past." She clearly had dreams of becoming a sensational romantic novelist, but, alas, she must make a living, so she is instead the jailer of Cecily and the guardian of her education and virtue. She, like the minister, makes constant moral judgments. Her favorite line, even to dead Ernest, is "As a man sows, so shall he reap." Repeating this often allows Wilde to show how meaningless and clichéd religion and values have become. As an instrument of the aristocracy, Miss Prism educates Cecily to conform to the dry, meaningless intellectual pursuits designed to keep the status quo. But, like Chasuble, beneath her surface she has a hedonistic streak; often her language slips when she ventures outside her Victorian appearance. She persists in inviting Chasuble to discuss marriage, pursues him diligently, and falls into his arms at the end.
Miss Prism is an appropriate character to uncover Jack's true history because she also is not what she seems. Wilde uses her to show what happens when dreams cannot be pursued in a society of strict social structure and stringent moral guidelines. Both she and Chasuble — with their lack of social opportunities — become servants to the system, promoting its continuation.