Deception is a huge part of this play because everyone is deceiving everyone. The expectation during this time period to be moral, Wilde uses this to create characters like Algernon and Jack who invent fictitious alter egos to be able to escape the strictures of propriety and decency. Other characters do this as well. Cecily writes in a diary, a detailed story about a man she claims to have a relationship named Ernest. Algernon goes along with this lie to make Cecily want to be with him. This parallels Jack's need to change his name so Gwendolyn will want to be with him. So, while both men are pretending to be "Ernest," they are deceiving the women they want to marry. Jack and Algernon take deception a whole different level in play in attempts to mask their doings, avoid their duties, and deceive their loved ones.
Class
This theme connects to every other theme represented in this play. Jack, a main character in this play, has no family, which is a big problem when it comes to marriage because where/what family you come from matters. In the Victorian world one’s name was the measure of one’s social status, so the fact that Jack doesn’t have any family is an impasse to his marrying Gwendolyn, a daughter of the titled gentry. Classes scrutinize the behavior of others so much that they fails to examine their own flaws and downfalls. This points to Algernon's inability to be self-reflective. Wilde's use of this theme represents this time period's importance of class and it's affects within every character.
Marriage
A big question in this play is if marriage is a positive thing or means to an end. The characters in this play have different ideas of marriage. For example, Algernon represents a mindset toward marriage that is more modern for this time period. He is skeptical about married couples and doubts that they are happy together. He is also scared to commit to just one woman. Unlike Algernon, Jack believes more in the traditional side of marriage. Like many plays/books of this time period, marriage is a big theme. In the play, Jack pursues Gwendolen’s hand, while Algernon pursues Cecily. Many things come up on their pursuit to win over these women, including Gwendolyn's hesitance to marry a man not named "Ernest" and Cecily's confusion when Algernon says his name isn't "Ernest." From the beginning to the end of the play, the argument about if marriage is a business deal or love is extremely prevalent.
Morality
Oscar Wilde looks at Victorian society is a very different way than many during this time period. He makes fun of the whole Victorian idea of morality as a strict body of rules about what people should and shouldn’t do. He plays on this with the title of this play, "The Importance of Being Earnest." Earnestness, which refers to the quality of being serious and sincere. The plot of the play is about the man who both is and isn’t Ernest/Earnest which presents a moral paradox. What Wilde wants us to see as moral is really the opposite of earnestness.
Being "Earnest"
When discussing this theme, it's important to understand the use of the word "earnest" in this play. The definition of the word is "serious in intention." Earnest can mean "smugness," "boringness," "self-righteousness," and many other words that Oscar Wilde saw as hallmarks of the Victorian character. However in this play, they aren't serious about the things they should be serious about. For example, Algernon and Jack who invent fictitious alter egos to be able to escape the strictures of propriety and decency.