For more info see these links:
http://www.askmoses.com/en/article/284,2060899/What-is-the-Jewish-view-on-cremation.html
The Jewish way of dealing with death is part of a larger philosophy of life, which views the human body as integral to one’s Divine service, so that even a body that is no longer alive is accorded the greatest consideration and respect.
The following is an excerpt from The Jewish Way in Death and Mourning by Rabbi Maurice Lamm:
Cremation is never permitted. The deceased must be interred, bodily, in the earth. It is forbidden-in every and any circumstance-to reduce the dead to ash in a crematorium. It is an offensive act. It does violence to the spirit and letter of Jewish law, which never, in the long past, sanctioned the ancient pagan practice of burning on the pyre. The Jewish abhorrence of cremation has already been noted by Tacitus, the ancient historian, who remarked (upon what appeared to be a distinguishing characteristic) that Jews buried, rather than burned their dead.
Even if the deceased willed cremation, his wishes must be ignored in order to observe the will of our Father in Heaven
Even if the deceased willed cremation, his wishes must be ignored in order to observe the will of our Father in Heaven. Biblical law takes precedence over the instructions of the deceased.
Cremated ashes may not be buried in a Jewish cemetery. There is no burial of ashes, and no communal responsibility to care, in any way, for the burned remains. The only exception is when the government decrees that the ashes be buried in the ground, and there is no other burial plot available to the family. For such unusual cases a portion of the Jewish cemetery must be marked off and set aside.
Jewish law requires no mourning for the cremated. Shivah is not observed and Kaddish is not recited for them. Those who are cremated are considered by tradition to have abandoned, unalterably, all of Jewish law and, therefore, to have surrendered their rights to posthumous honor.1
One of our Thirteen Principles of Faith is that there will be a resurrection of the dead. Someone who willingly requests to be cremated is essentially rejecting this principle.
Concerning such a person the Mishnah says (Sanhedrin 10:1): "All Jews have a portion in the world-to-come . . But these do not have a portion in the world-to-come: one who says, 'Resurrection of the dead is not from the Torah'..."
It is, however, possible for a descendant of the deceased to give charity and do mitzvos for the benefit of his/her ancestor and thus can gain atonement for the soul of the departed. Even if this condition is not met, the soul (which is divine and eternal) will come back for the Messianic Era but will have to be clothed in a different body.
