Dante's "Inferno" is a religious quest through the realm of hell. Part of his Divine Comedy, Dante's Inferno is a journey through the levels of hell and the sins that place humans there. The work itself is rather revolutionary in how it categorizes human sin. Prior to the work, the perception of the element of vice was seen in a monolithic form: It was bad. Dante evokes a level of complexity in the perception of human evil in its categorization into different realms. It is interesting to note that he actually includes current people of his day in different levels of the purgatory, indicating that Dante believed that the issue of human failing is an all too human one that pervaded all levels of society. Dante's categorization of hell and each corresponding level contains an appropriate punishment for each sinner. For a very religious society, to examine the complex nature of sin and vice was revolutionary, and in this respect, the purpose of the Inferno was to spare no one and ensure that each individual reading it understood where they were, and where their sins would be categorized. Taking place over Good Friday weekend, Dante ensured, through his guide Virgil, that a spiritual education would be endured through the nine levels, concluding with the ninth level where the frigid confines contain the souls of betrayal. In concluding his journey through hell on the note of disloyalty, Dante makes very clear that all human beings are responsible for their actions and sin is an essential part of the human predicament. The inferno is the first stage en route to the redemption of Paradiso, where Beatrice leads Dante to a vision of God where all opposites of merged and the height of literary comedy is achieved, where the good, the true, and the beautiful supplant his infernal vision of human misery and mistake.
Let me give an overview of the purpose of Dante's Inferno, but please realize that analyzing this classic could be a book itself. Inferno is the first part of Dante's Divine Comedy and is set in 1300. The people in the story (which was actually a poem, but looks less like one now through its translations) were real people who were in the different levels of hell. The story is obviously meant as an allegory and makes sense at a literal level as well. Nonetheless, it is a story of poetic justice--getting what one deserves and while Judeo-Christian/Catholic in nature, it is not unlike the Hindu notion of karma.
The text urges the reader to see through to the nature of the sin and thus understand the sin itself. Sin is divided into many levels in the story, but the main ones (heirarachally) are self-serving or self-indulgent, violent sins, and malicious or mean sins.
The examination of these things serves as the basic purpose of the story.