Hidden Knowledge in Judaism

 הַנִּסְתָּרֹת--לַיהוָה, אֱלֹהֵינוּ; וְהַנִּגְלֹת לָנוּ וּלְבָנֵינוּ, עַד-עוֹלָם--לַעֲשׂוֹת, אֶת-כָּל-דִּבְרֵי הַתּוֹרָה הַזֹּאת.

The secret things belong unto the LORD our God; but the things that are revealed belong unto us and to our children for ever, that we may do all the words of this law.

People have been hounding me to write about the subject of hidden/secret knowledge within Judaism for ages, and I just haven't found the time. Many Muslims are of the belief that Jews commonly practice black magic. I want to differentiate between spiritualism/Kabbalah and black magic. I also want to differentiate between modern pseudo-Kabbalah and the original Kabbalah. Black magic is the casting of spells or incantations to hurt or help individuals, the invoking of jinns/angels/demons, or the making of covenants with evil spirits, including false gods. This practice has been condemned by the Jewish prophets with strong words, yet many Jews practiced it. 

Isaiah 28:15-18

Because ye have said: 'We have made a covenant with death, and with the nether-world are we at agreement; when the scouring scourge shall pass through, it shall not come unto us; for we have made lies our refuge, and in falsehood have we hid ourselves'; Therefore thus saith the Lord GOD: Behold, I lay in Zion for a foundation a stone, a tried stone, a costly corner-stone of sure foundation; he that believeth shall not make haste. And I will make justice the line, and righteousness the plummet; and the hail shall sweep away the refuge of lies, and the waters shall overflow the hiding-place. And your covenant with death shall be disannulled and your agreement with the nether-world shall not stand; when the scouring scourge shall pass through, then ye shall be trodden down by it...

Jeremiah 44 also speaks about the sin the Jews offering sacrifices to the Queen of Heaven, a local deity, and Jeremiah's strong words against this sin. The Jewish people of his time told Jeremiah that they did not care about his words and would continue to offer sacrifices to this false goddess. The Jewish king Ahab was famous for introducing the worship of the pagan god Ba'al into Israel. Although this black magic was common among ancient Jews, it is not permitted or acceptable under Jewish law. The many prophets sent to the Jewish people condemned the practice and described God's contempt for it, yet it continued. 
Modern pseudo-Kabbalah derives almost entirely from the Zohar, a misguided book almost certainly written by Moses de Leon. Devotion to this book has led many from the path of righteousness. Mori Michael Shelomo Bar-Ron wrote a brilliant piece titled "The Zohar Controversy: A Crisis of Priorities" which he has unfortunately deleted. In it he delineated some of the ways that many modern Jews have been led astray, going so far as to declare modern men demi-gods and misguidedly failing to observe important Jewish holidays in favor of so-called mystical holidays. This deviance from the straight path is tragic.
Now that these two have been discussed, I can begin a discussion of legitimate hidden knowledge in Judaism. There are, as I have mentioned in other parts of my blog, two Torahs: the oral and the written. From what little we know of the original Oral Torah, it explained parts of the written Torah that are unclear, like the creation story in Genesis. The original Kaballah was part of this knowledge. It was to be taught only to extremely promising students studying to become rabbis who had attained forty years of age and were married. The rabbis famously warned in Hagigah 14b of the danger of the original Kabbalah: they spoke of four who entered Pardes (the Garden), by having received this knowledge. Of the four, one lost his mind, one lost his faith, one died, and only one escaped injury. This knowledge was considered so powerful and so destructive, that there were strict limits on who could learn it and teach it. Of those allowed to learn it, they were not even taught the full text: they were taught only chapter headings, and were meant to deduce the rest on their own. The original Kabbalah was a huge part of the hidden or secret knowledge within Judaism. Unfortunately, it did not survive to the present day. However, many of the quotes attributed to secret Jewish knowledge by Muslim scholars are similar to items within the Zohar, such as the foretelling of the rise of Islam. Whether the Zohar was written with the full knowledge of the rise of Islam or whether it was an organic, living oral tradition dating back to the time of Moses is unknown. 
Another part of secret/hidden Jewish knowledge is knowledge that is forbidden to be taught to non-Jews. An example of this is a story from the Talmud which it is nearly impossible to find a translation for in English, so I will paraphrase it for you. A man was flogged by the Jewish court, led by Rabbi Shila, for having had a sexual relationship with a non-Jewish woman. He appealed the case to the non-Jewish magistrate and demanded that the Jewish court be disbanded. The non-Jewish magistrate asked the Jewish court the reason they had illegally flogged the man, and they responded that he had had sexual intercourse with a donkey. The magistrate was so appalled that he questioned why they had not killed him instead, and went away. The man questioned the court about why they would lie about his conduct in front of the magistrate; Rabbi Shila said he had not lied, citing Ezekiel 23:20: "And she [Israel] doted upon concubinage with them [non-Jewish nations], whose flesh is as the flesh of donkeys, and whose issue is like the issue of horses." The man then went to inform the magistrate that Rabbi Shila had called him a donkey, and Rabbi Shila issued an instant ruling that since this would lead to his own death, it was permissible to kill the man, and he struck the man dead instantly. Any knowledge about Judaism that is likely to lead to hatred for Jews and the death of Jews is forbidden, on penalty of death, to be taught to non-Jews.
In summary, there are two main categories of sinful magic historically practiced by Jews: black magic and pseudo-Kabbalah; and there are two kinds of secret knowledge that are condoned within Judaism, the original Kabbalah and other parts of the Oral Torah, and knowledge that would be harmful to Jews if it became public knowledge. I hope this clarifies the subject of Jewish practice of magic and secret knowledge within Judaism for you. If you have any further questions, please do leave a comment. Or a complaint. I don't make it my policy to moderate comments.