Rebbe Nachman explains to us (Likutei Moharan I: 36:5) that the Torah has two potentials — for life or for death. Our Sages teach us: “‘Place them’ …” (Deuteronomy 11:18) — if he is deserving, it becomes his elixir for life; [but if he is not deserving, it becomes his potion of death]” (Yoma 72b).
The Rebbe points out by citing Yoma that depending on one’s approach, the Torah can be either an elixir of life or a potion of death. If a person can approach the Torah with the thought of drawing closer to Hashem, then the Torah one learns is an elixir of life.
However, if a person’s interest in Torah is not directed to serving Hashem, then the Torah becomes a potion of death, G-d forbid. The Torah this one studies will mislead the person and only strengthen the evil traits the person already possesses. There are many examples of such a person: someone who studies Torah as an intellectual pursuit and rejects its obligations, someone who studies Torah in order to argue with the Torah scholars or mock them, or someone who studies Torah simply to receive financial gain or honor.
“The ways of Hashem are straight; the righteous will go in them, [but the wicked will stumble in them]” (Hoshea 14:10). Our Sages (Nazir 23a) teach that it is possible for two people to perform the same act, and while for one that act is a mitzva, for the other it is a sin! Rebbe Nachman warns us that the person can choose whether to walk in the path of the righteous or, G-d forbid, otherwise.
Hence, our Torah learning can turn out for our good or otherwise based solely on our intentions. If we study Torah in order to get to know Hashem better and to draw closer to Him, it becomes an elixir of life for us. However, if our learning is for personal, less-pure reasons, G-d forbid, it becomes a potion of death. If we realize our intent in studying Torah is not so pure, we must at least want to study with pure intentions, and can then cry out to Hashem to help us merit to correct our less pure approach.
Based on Likutei Moharan, Volume V (see notes there)