Higher Law
The main theme of the play is that there is a higher law that man must obey. It is above any edict of a politician or king. Kreon has ordered Polynices' body to remain unburied for the wild animals to eat in order to re-create structure in Thebes. But Antigone attempts to bury his body, even though the sentence for doing so is death, because she does not live by Kreon's law but by the laws that are even higher than those he sets forth.
Pride
Kreon has the opportunity to bury Polynices at any time during the play, but he chooses to remain steadfast in his law. He believes he is making Thebes back into the great power it once was by getting the people in line through this law. But the truth is that he is blind to the reality of what he is doing, and even when asked to overturn his law he won't, to the death of his son and wife after Antigone.
Sacrifice
Antigone could very easily not bury her brother and live a comfortable life. She was once the daughter of Oedipus the King. But she cannot allow her brother's corpse to rot and be eaten by wild dogs and buzzards, she must bury him so that he may enter the afterlife where their parents await him. And she will do this at the greatest price which she pays for with her life. And she becomes the symbol for the people of Thebes and their conscience.
