"SATAN UNMASKED Satan is: a. Any thought, feeling or action performed unconsciously. b. Ignorance of God and spiritual Truths. c. Hatred of all that is truly good and decent and healthy. d. The same as being insane, psychopathic, paranoid, egotistical. e. Anything harmful to anyone, such as cruelty, slander, deception. f. Lying by calling evil good and good evil. All these inner states express themselves outwardly in crime, violence, misery. You need not be part of it."
... that there actually IS some kind of "evil force" that affects -or can affect- human beings.
The expression -"selling your soul to the devil"- has a lot of truth to it. There's a spirituality which is connected to evil ... just as there is for a spirituality connected to good.
Repentance is changing your mind and getting tuned in to good spirituality once again but ... there are occasions where the COST of doing that is too great for some. They've "crossed over a line" from which there is no returning ... without losing physical life. So they push on in their evil and eventually destroy themselves. But ... they take a lot of others with them.