HuffPo ran a piece discussing a way to "instantly" reverse negative thoughts. It's an old technique, really, as old as Albert Ellis and his Cognitive Emotive therapy, which I learned about in the 1970s. It basically involves having a dialog (whether with a therapist or with yourself) where you challenge your own thoughts. If you think you're a failure, you can ask yourself, "Is it true that I fail at everything? Are there some things I am good at?" Surprisingly, the technique often works, bringing relief by giving you a wider perspective into your own abilities.
NPR's Invisibilia ran "Dark Thoughts," a piece that featured a story about a man who, after watching a violent movie, started having intrusive thoughts about stabbing his wife. He eventually got help from a therapist who told him that such thoughts happen, and he can just dismiss them when then do. Accept that they arise and pay them no heed. It worked. At least in the sense that this man stopped thinking he was a psycho or that he harbored a secret hatred for his beloved wife.
My Mom used to say "I had a little talk with myself" when she felt was going off-kilter.
Stories like these make me wonder if our minds are really our own. Rather than the orderly parade of thoughts and emotions under control of the bandleader of consciousness, our minds seem more like an unruly mob, throwing out half-mad suggestions and acting impulsively on its own.
It's the 21st century, and we are still just getting the hang of how our own brains work! Imagine what it must have seemed like for people experiencing this in ancient times. Some thoughts don't seem to be our own--where could they come from? Must be from outside, from a malevolent being urging us toward evil! Next thing you know, we have devils, possession, hell and all the rest.
It's impossible to discount the existence of external evil. For all I know, there may well be a dark entity working to do us harm. But it seems apparent that there is plenty of darkness between our own ears. Before leaning too heavily on Satan and his minions, let's talk ourselves out of some bad thoughts and impulses if we can. Let's us pharmaceuticals to mop up some more. And if there's anything left over, well, let the Devil take the hindmost!