What are the major concerns/themes of Hamlet?

Since the play begins with a question and is full of
philosophical questions, the two major concerns of Hamlet
are:

Is man supposed to be an active agent or
a passive suffering creature in the
world?

Hamlet's famous "To be or not to be"
monologue presents two opposing views: "suffer the slings and arrows of outrageous
fortune" or "take arms against a sea of troubles"?

Hamlet
is not given much of a choice by his father, the Ghost: revenge him and leave Gertrude
"to heaven."  Hamlet knows he's not cut out to be an avenger, and most of his anger is
not directed toward the males; rather, it's focused on his mother.  So, how can he
summon up the courage to kill a heavily guarded king who may or may not be guilty?  It's
an existential and profoundly moral dilemma.  Hamlet finally decides, "Let be...the
readiness is all."  He says we must live ready to
die.

What is the nature of death and the
afterlife?

There's moral confusion in the
play and with Hamlet himself.  The Ghost's appearance confirms a supernatural afterlife.
 Hamlet must find a way to kill Claudius and send him to hell, but killing will also
send Hamlet to his death and hell as well.  There's little chance Hamlet can carry out
the Ghost's wishes and both save his life and guarantee his afterlife in
heaven.

Also related is the nature of the heavenly father:
how can Hamlet's father's Ghost (symbolic of the Old Testament
Yahweh) condone revenge if he knows Hamlet is a Christian?  So,
Hamlet becomes a Christ-figure, torn between the expectations of his vengeful heavenly
father and his own beliefs in Christian forgiveness.