I saw a show on the History Channel about the witch trials. The show was able to link a fungus to almost all of the witch trials in history.
The Salem witch trials are misunderstood. There was a fungus growing on the rye which they used to make bread, about half of the town was affected by it, they had hallucinations and spasms as the fungus constricts blood vessels in the brain. They looked for a cause but since the fungus grows in the seed pods, and shapes itself much like the seeds, there was no visual evidence that that was what caused it. The fear was astounding, the hallucinations epic, small girls able to fight with incredible strength etc. With the limited science of the time they had nothing to attach it to the physical.
If you want an example how Christianity was directly misapplied look to the attacks on the Knights Templar and to the Inquisition. The Crusades were in answer to the Muslims taking over half of the world, yes once victory had been met they pushed too far but clearly it wasn't an example of only Christian misdeeds.