The Zohar is a commentary on the Hebrew Scriptures and the primary source of the beliefs of Kabbalah, a mystical form of Judaism. According to Kabbalah, this text was written in the 2nd century AD by Shimon bar Yochai. Supposedly, bar Yochai was inspired by visions from the angel Gabriel to record secret, powerful knowledge about interpreting the Torah. Unlike other Jewish commentaries on the Torah, known as the Mishnah or Midrash, the Zohar is heavily mystical and borders on an occult- or witchcraft-based approach to spirituality. Kabbalists believe that Jewish leadership during the Roman era considered such knowledge to be too powerful for the common man, and so they suppressed it.
According to the Zohar, God’s message in the Torah is meant to be understood at four levels: literal, allegorical, Rabbinic, and secretive. In other words, the more powerful and truthful purpose of the Torah is only accessible to those with special knowledge and insight, per Kabbalah. This places the Zohar and Kabbalah firmly in the sphere of Gnosticism and mysticism.
The text of the Zohar was unknown until first published in the 13th century by Moses de León. De León claimed the writings to be traditions passed down from Shimon bar Yochai many centuries before. However, most modern scholars, Jewish and otherwise, believe that de León himself actually composed the Zohar’s content. De León’s publication came from a place and era when Gnostic concepts were in fashion. Also, no mention is made of the Zohar or its contents in any midrash known prior to de León’s publication of the Zohar.
Mainstream Christianity considers the Zohar and Kabbalah to be false teachings in the same vein as other Gnostic and mystical cults. The same is true of all major sects of mainstream Judaism, although some Jewish scholars see the Zohar as useful for gaining insight into Jewish thinking, and some use the Zohar to provide additional opinions on the meaning of the Torah.