The darkness has always been there. Some have chosen to shine light on it. However, I agree, it can be a slippery slope and can attract dubious individuals losing themselves in the criminal mindset. In some places of the World, this is needed. In others, not to such an extreme. It goes back to the idea of: stare too much into the abyss, it will stare back. I hope to never become the monster I need to be to eliminate the threat. However, having "dark tools" in my toolbox, is not bad for me. Find a balance.
Regarding the picture of the satanic bible with the hands over it, is more of a statement or perspective of what that individual experienced. His reaction to it. I was working with this individual during that weekend seminar. Why he chose that picture to express himself instead of something else, is because of his view on the violence we learned. It was evil for him.
Keep your morals, keep your goodness, and evil shall not consume you.