As the ancient Roman historian Tacitus noted, Jewish custom mandates burial in the earth, an obligation treated with gravity by the Hebrew Bible and even more so by the rabbinic tradition. Thus cremation, not to mention recent techniques like cryonics, are forbidden by halakhah. Shlomo Brody explains that these attitudes stem from the biblical idea that the divine image inheres in every human being:
Humans, according to the Bible, were created from the earth, and in death we return to our source. This reminds us during our lifetime of our modest origins, while further encouraging us to utilize our time on earth to merit eternal life in the world to come alongside the resurrection of the dead, which will be granted only through God’s grace.
It was precisely out of a rejection of these notions that many Westerners favored cremation, when new technologies developed for efficient incineration in the 1870s. In modern cremations, bodies are incinerated at four-digit temperatures for two to three hours. Bone fragments and other residue are further pulverized before they are collected and returned. . . .
Interestingly, in some Eastern religions, cremation is utilized precisely because of a belief in the continued (and primary) existence of the soul, with the body’s destruction indicating its inconsequence. [But] Jewish law rejects this attitude toward the physical body. While the soul and its eternal life may have primary importance, the body is still seen as a holy vessel that allows us to manifest our inner spirit. [Likewise], a Torah scroll that has become blemished must still be treated with sanctity and properly interred. All the more so with the human body, which was created in God’s image and allows us to bring the divine word into the world.