If God had not "Shut the gate", and closed Eden permanently,  Adam and Eve would have been kicking down the door to get back in.  But in Gen. 3:24, we read: "So he drove out the man; and he placed at the East of the garden of Eden Cherubims, and a flaming sword which turned every way, to keep the way of the tree of life."  They weren't getting back in.  And any hope of eating of the Tree of Life was gone.  Like I said the other day:  "Dead man walking."  It was just a matter of when.

They were all stuck with each other--outside the gate.

Gen. 4:9  "And the Lord said to Cain, Where is Abel your brother?  And he (Cain) said, I know not:  Am I my brothers keeper?"

Anger, murder, and now a huge lie.  In John 8:44 we read, "You are of your father the devil and the lusts of your father you will do.  He (Satan) was a murderer from the beginning, and abode not in the truth, because there is no truth in him....for he is a liar, and the father of it (lying)."

And after Cain lies to God, he insults God's intelligence!!  He asks God a question--Cain thinks he can fool God.  He does not confess what he has done, and just like his parents before him, he is definitely not repentant.

"What have you done?"  God asks Cain.  And  if we were to put it into today's vernacular,  God is saying:  'Don't you know that I know everything!  Haven't your parents taught you anything about me?'  Then God tells Cain that, "...the voice of your brother's blood cries unto me from the ground."

And then God places a curse on Cain.  So far, everyone is cursed except Abel, and he's dead.

Things aren't going too well.