Тhe Zohar is written for people who wish to attain the purpose of creation and yearn for the Light that brings them back to the Source. Without the Light, it’s impossible to correct our desires and unveil the Creator in them. This is why The Zohar, like the entire Torah, can either be the “elixir of life,” or a “deadly poison.”
One has to check his intention before approaching The Zohar and the Torah, in general. If with the help of studying he wishes to attain the Light that Reforms, the Torah becomes an elixir of life for him, as it is written: “I created the evil inclination and handed down the Torah for its correction, because the Light in it Reforms.”
If, however, a person isn’t yearning to bestow, meaning return to the Source, but studies The Zohar motivated by his will to receive pleasure and be filled; if he is pursuing other objectives (which is called “idolatry”), then, his studying turns into a “deadly poison” and distances a person from the purpose of creation.
Therefore, we must be cautious and remember that during our studies, especially while reading The Zohar, we are preparing our desires for the Creator. We want Him to give our desires the strength to bestow and as a result, to reveal Himself in these forces of bestowal.
From the 1st part of the Daily Kabbalah Lesson 5/27/10, The Zohar