What best identifies the central theme of the story of Oedipus Rex?

The
central theme of the play would be the folly of trying to change one's
fate. For ancient Greeks, fate was determined purely and solely by the gods. It was therefore
considered impious to ignore the dictates of fate and try to create one's own destiny in open
defiance of what the immortals had planned.

That is precisely whattries to
do. He ignores the prophecies of the blind seer who bravely tells Oedipus to his face that he is
the one who killed his father. By extension, this means Oedipus has also committed the very
grave sin of marrying his mother, . Unsurprisingly, Oedipus is unable to face up to such a
terrible truth and accuses Tiresias of conspiring withto remove him from the throne of
Thebes.

In challenging Tiresias like this, Oedipus is defying the gods
themselves, for Tiresias has been given the special power to determine the will of the gods. His
prophecies, therefore, have the status of holy writ. However, Oedipus is too vain, too foolish,
and too proud to recognize this. He'd much rather continue to delude himself instead of facing
up to the terrible truth of what he's done.