Both. Dante, like all Renaissance intellectuals, was certainly very familiar with the classical western canon and uses a whole bunch of characters from Greco/Roman mythology in his narrative. However, the Inferno is first and foremost the artistic outburst of an exiled politician. He was writing a reaction to contemporary politics, to be read by a hyper-educated elite which had cast him out, disregarding his loyalty to Florence (incidentally, this is also why his contemporary references go so far beyond Tuscan politics. The courts at Ravenna, Rimini and Verona were more than happy to welcome him). The Divine comedy, as a study of Morality, damns Dante's enemies, using a complex system of allegories to show just how immoral they are, and touts the virtues of those who had welcomed him.