Jewish tradition prohibits the cremation of a deceased body, because it impedes the body’s natural decay. Rabbis believe cremation and the burning of bodies inflicts impurity on the body. When a body is cremated, the ashes are usually not buried in the ground, thus not fulfilling the verse “for dust you are, and to dust you shall return” (Gen. 3:19). Once a body has been cremated, Jewish tradition does not allow the ashes to be buried in a Jewish cemetery or to receive a ritual funeral (this does not apply to bodies that have been accidentally incinerated). Some rabbinic bodies, however, have allowed the ashes of cremation to be buried in a Jewish cemetery so that at least part of the deceased is returned to the earth. Cremation also is contrary to the Judaic idea of the resurrection of the complete body following the arrival of the Messiah.
Sources: Eisenberg, Ronald L. The JPS Guide to Jewish Traditions. PA: Jewish Publication Society, 2004; Kolatch, Alfred J. The Jewish Book of Why/The Second Jewish Book of Why. NY: Jonathan David Publishers, 1989; Kolatch, Alfred J. The Jewish Mourner's Book Of Why. NY: Jonathan David Publishers, 1996.