In Oedipus Rex, how is Oedipus led to commit the sin of killing his father and marrying his mother?
Oedipus is a victim or a tool of fate, a destiny that he cannot escape.
Oedipus, who is abandoned to die by his real parents, is rescued by a herdsman and given to the King and Queen of Corinth. Growing up a Prince, Oedipus learns that the King and Queen are not his birth parents. Seeking the help of the oracle at Delphi, he learns of the prophecy of killing his father and marrying his mother and is so horrified, that he is determined to outwit the prophecy. He leaves Corinth.
As he travels near Thebes, he is assaulted by an old man and his servants, he strikes back, killing the man. Oedipus does not know that the old man is Laius, his real father.
He confronts the monster Sphinx, answers the riddle and is hailed as a champion. Approaching the widow, Jocasta, Oedipus seeks advice about the prophecy. She does not believe in prophecies, since the one told to her did not come true, her child died.
When he discovers that his father, the King of Corinth has died from natural causes, Jocasta tells him that it is proof that the prophecy is never going to come true. The two marry and have four children. Oedipus has married his mother.
Events in the story unfold to make Oedipus believe that he has avoided fulfilling the prophecy, when in fact, his fate is a set path, a road he cannot avoid.
It is a sin of ignorance. Because of the prophecy that his son would kill him and marry his wife, Laius had his infant son taken to be killed. Instead, he is raised in a kingdom away from Thebes. When he hears the prophecy about himself, he leaves that kingdom (thinking erroneously that he is avoiding the prophecy), and while on the road kills Laius (not knowing he was his real father). He then goes on to Thebes, becomes the King, and marries Jocasta (his mother). And you thought soap operas were twisted tales?!
His ignorance is further complicated by his hubris, the arrogance that he can outsmart the prophecy. This is what ultimately brings about his downfall.
He's not--he does not kill his father or marry his mother in the play--as he seeks the killer of Laius, he winds up realizing that he did do these things in the past. This awareness leads him to sees who he really is, and it is who he is that is the sin (actually, the error)--not what he did. Oedipus has violated one of Apollo's two ruling oracles from Delphi: "Know Thyself," and the play is about correcting Oedipus's knowledge of who he is, a human
with bad blood, a polluted existence and returning him to his place in relationship to that of the gods, thus restoring the order of society--even the greatest human is not as great as the gods.