The resurrection of the dead will occur in
the messianic age. When the messiah will come to initiate the perfect
world of peace and prosperity, the righteous dead will be brought
back to life and given the opportunity to experience the perfected
world that their righteousness helped to create. The wicked dead
will not be resurrected.
Question: There
is a concept in Judaism, that at the time of the Messiah all the
dead will be resurrected. And we know that also at the time of the
Messiah, all the Jews will return to Israel. So what will happen?
Answer: Those
buried outside of Israel will "roll" through underground
tunnels, and be resurrected in Israel. Apparently who traveling
through these tunnels will cause some distress.
It is for this reason that Jacob requested
that he be buried in the Land of Israel, and why many other Jews
over the centuries have followed suit. (See Rashi - Genesis 47:29)
Nevertheless, there are many great Jews who
are buried outside of Israel, who will have to make this journey.
In fact, the Talmud asks: If God would not permit Moses to lead
the Jewish people into Israel, why did God go further and insist
that Moses also be buried outside the land?
The Midrash (Devarim Raba 11:9) says that
Moses was buried outside of Israel, so that at the time of the Messiah,
Moses will serve as a merit to make things easier for everyone else
buried outside the land. Similarly, this is why the prophet Ezekiel
was buried in Babylon, and Mordechai from the Purim story "the
book of esther" was buried in Persia. (See"Sifsei Kohanim"):
Simply In Judaism by being a good Jew, dead is never the end.
Cremation within Judaism
With today's high 
cost
of burial casket, tombstone, plot of land many are opting for cremation.
What is the Jewish position?
Judaism permits only burial. The source for
this comes from the Torah, where God tells Adam: You will return
to the ground, for it was from the ground that you were taken. (Genesis
3:19)
Judaism not only specifically forbids cremation, but insists on
a very simple burial directly into the ground. Let's understand
why.
Upon death, the soul goes through a painful
separation from the body, which until now had housed the soul. This
process of disengagement occurs as the body decays. When the body
is buried, it decays slowly, thereby giving comfort to the soul
as it disengages from the body.
This decay is crucial, which is why Jewish
law forbids embalming or burial in a mausoleum, which would in fact
delay the decaying process. Also, Jews are buried in a wooden casket,
which decays more rapidly. Similarly, Jewish law dictates that burial
take place as soon as possible after death. (In Israel, funerals
often take place on the same day as the death.) All this is for
the benefit of the soul.
One reason that Judaism prohibits cremation
is that the soul would suffer great shock due to the unnaturally
sudden disengagement from the body. As the Talmud says: Burial is
not for the sake of the living, but rather for the dead. (Sanhedrin
47a)
Cremation/Resurrection: Jewish tradition
records that with burial, a single bone in the back of the neck
never decays. It is from this bone -- called the luz bone -- that
the human body will be rebuilt in the future Messianic Era when
all the dead will be resurrected. With cremation, that bone can
be destroyed, and the resurrection process stymied.
In fact, someone who chooses cremation is
as if he does not believe in resurrection. This is a fundamental
of Judaism, as expressed in Maimonides' classical "13 Principles
of Faith": "I believe with complete faith that there will
be a resurrection of the dead, whenever the wish emanates from the
Creator."
