Some people think there is not such concept as demons in the Torah even though they are quite well documented in the Ari and Zohar and the Talmud itself.
The trouble is people in the religious world tend to think they are immune by the very fact of their being religious.
The dark side, evil, teachers of Torah are in fact devils in disguise. This is a serious problem in the religious world much more than in the secular world.
The reason is to a large degree is that there is a close connection between good character and holiness. Since the Jewish secular world, with all its flaws, tends to stress good character above all, therefore they tend to be more protected from the Dark Side than the religious who stress rituals at the expense of human decency.
[I am no expert on this subject and in fact I have no idea how to avoid the Dark Side at all. All I can say is all the supposed solutions seems to be in fact traps.]
Teshuva repentance in a practical sense seems impossible. For when one tries to undo something he has done wrong the general result is to make things worse-as we see in the Torah by the people that tried to go to Israel after the events of the spies when it was decreed the generation of the desert should not enter the Land of Israel.