Why did Chaucer bring the gods into "The Knight's Tale"?

The action of "The Knight's Tale" is set in Athens and Thebes in ancient Greece. Given the setting, it was perhaps inevitable that the ancient gods would be invoked by Chaucer at some point. But he introduces them mainly to highlight the superiority of Christianity over pagan religion in explaining what happens in the world, especially in relation to love and death.
Here, the gods intervene in human affairs as they often do in Greek mythology. The gods have their champions, and in this tale Mars and Venus squabble over which of the warring knights will prevail. On the face of it, it seems that we're being presented with a pagan worldview, where the gods are all-powerful and everyone just has to accept the fate that the immortals have laid down for us. Theseus, however, is given to us as a kind of proto-Christian, a Christian before his time. He advances the notion of God as a prime mover, a superior being that sets the ball rolling, as it were, creating the entire cosmos as a great chain of love that holds the everything together. So the death of Arcite, like all deaths, is not as the result of some arbitrary act by the gods but part of a divine, orderly plan in which there is a reason for everything and everything has its proper place.