Wait, where'd Zeus come in?

On page 141, in Canto 14, in lines 49 - 60 where Dante and Virgil's meeting with Capaneus is described, "And he himself who picked up what I said, hearing me ask my guide about him, cried, 'What I was living, so am I still, dead! Jove can go break his blacksmith's back with work, from whom in wrath he took the thunderbolt that ran through me on my last day on earth -- or wear the others out in endless shifts under Mount Aetna at the pitch-black forge, hollering, "Vulcan, help, I need your help!' As he did on the Phlegran battlefield, and hurl his lance through me with all his force -- he'd get no joy in his revenge."'"

Whoa, whoa, whoa -- back up. Why are the Roman gods mentioned here, in a Christan comedy? And not just mentioned, but actually doing godly acts, like killing people. Since when was blaspheming non-existent gods worthy of putting you in hell? Also, Plato and Socrates, both of whom we found in the first ring of hell, emphasized in their writings that they did not truly believe in the gods of their society. If Dante is being consistent, why are they up there with the unbaptized, instead of down here with the blasphemers?

~Hannah