What assumptions does Creon make about the gods?
Creon assumes that the gods would have no pity for Polyneices, since he took up arms against the city of his birth. When the leader of the guard tells him that someone tried to bury the corpse he replies: "For thou sayest what is not to be borne, in saying that the gods have care for this corpse." He adds, "Or dost thou behold the gods honouring the wicked?" suggesting that he assumes the gods specifically wish that his command--that Polyneices not be buried, but be left for wild dogs to devour--be followed to the letter.
After he sends Antigone to be entombed alive as punishment for her illegal act, Tiresias--a seer--comes to him and warns him that the gods will turn on him now, because:
Thou hast thrust children of the sunlight to the shades, and ruthlessly lodged a living soul in the grave; but keepest in this world one who belongs to the gods infernal, a corpse unburied, unhonoured, all unhallowed. In such thou hast no part, nor have the gods above, but this is a violence done to them by thee.
Tiresias means that Creon has cast righteous people into the tomb and has further enraged the gods by passing a law that a corpse was to be unburied and unhonored--to be left for carrion birds and dogs to gnaw his bones. He was wrong about what the gods want, and he has wronged both Polyneices and Antigone, and will pay the price.