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."
