Dante's "Divine Comedy", of which the "Inferno" is part, is not a traditional oral epic but a highly literate work that mingles elements from classical epic with a new style of extended Christian allegory seen in many medieval works, and designed to be interpreted by the sorts of allegorical reading discussed in Dante's prose works.
The underworld journey, or journey among the dead, is an element of many traditional epics, including Homer's "Odyssey" and "Gilgamesh". The notion of Virgil as a guide links the "Divine Comedy" explicity to the earlier Latin epic, Virgil's "Aeneid." The religious content is also not uncommon and equally typical is exemplification or narrativization of religio-moral precept. The nature of the narrator as spectator, however, is somewhat unusual.